Refinement? Arguably the v3 runs a little rougher and although it makes more power going to DOHC, the powerband also moved up 500rpm. So you loose a bit of the low to midrange torque generally welcomed in daily city rides.
Parts wise, I say the v3 is worth the upgrade. You get better forks, marginally better front brakes, the upgrade to twincam and 5 extra HP, and other minor upgrades to mirrors, gear indicator. It does however packed an extra few kilos of weight.

Not sure if I'm getting the versions right though.

There is the v1 and v1 facelift, the V2 which is the UG, and the v3 is the touring model.

I'm assuming you are referring to the v3 as the UG where the most significant upgrade happened.

If you appreciate the bits, then there is no different with the UG.

I think you get saddle stays, a tail rack, windshield , lower (pretty useless) fake skid plate, hand guards and and an improved crash bar design that more protects the sides of the radiator.

Whether it is worth it or not, depends if you are going to outfit it with similar aftermarket parts, its still going to cost 800+ for some similar parts. A Givi tail rack alone is going to run 300ish.

If thats the case, just get whatever used dominar. They are going cheap nowadays. Seen them routinely going for 5k or less.

Needs experience to see. Usually take note on the wear and tear of the grips or sections of the bike that comes into contact with the rider or the general condition of the bike.

However, its not rare to see Dominar's with low mileage, as many of these are bought by first time B Full riders, either for a practice bike for the test and upgraded soon after or the owner just gave up on B full as was in the case of my bike. It only had 3600km on it when I bought it used 1 year old with hardly a scratch on it.

If this is to serve as your practice bike, I wouldnt sweat it too much as it would be a temp bike anyway.

Did entertain the idea of selling my Dominar, but at these sort of 2nd had prices, I'm just keeping the Dominar as a spare bike, used to get groceries as it has 3 boxes.  My V1 facelift is probably worth only 5k now (half that if i were to trade it in), but I only bought it at 8500 so for 4 years and 70k km I had it, the depreciation is actually negligible.... ROI achieved in year 3. The bike is "free" now.

the gold engine case bikes are the first batch. Its coming out to 6-7 years now. Having only 2000km sure raise eyebrows. No way of telling if the bike has an accident before unless you can get a good mechanic to see it. There will be telling signs though if you see any newer plastics or touch up parts. a 2000km bike should not need anything replaced.

even if it was not crashed and in perfect aesthetic condition, the battery is probably shot, tyres are expired and most of the rubber hoses and such would be dry rotting, fork seals shot and all fluids need replacement.

I suggest you shop for a newer low mileage UG or V1 facelift (black engine case, gold wheels) at 5-6k. At these prices a used Dominar is going for, best to avoid the oldest of them since there isn't going to be much price difference.

The most definitive sign of a low mileage bike is the tyres, especially if it comes with something uncommon in our market out of the factory. My 400 for example had the stock Dunlop Sportmax on it, which is not available in the Malaysian market last I checked, so it was really easy to tell that it really is a low condition bike.

I also noticed that bikes in KL / urban Selangor tend to have higher average mileage than Penang and Johor (albeit less so). So if you are getting something from Pahang for example, I would believe the mileage is probably genuine.

I won't worry about RV of any of these cheap bikes especially if you buy one used. Just view it as scrap value.

My advise. Dont bother with new if its just for a training bike.

First, you are going to drop it if you are doing things right with your training. To learn, you have to push the limits, especially for low speed maneuvers, which will inevitable lead to some jatuh bodoh.

Second, dont expect good RV

Third, you will outgrow it very very quickly and buy a bigger bike in a year or 2.

Dont get me wrong, the Dominar is a great bike to get started with...don't think there is any doubt on this point. But it lacks the longer distance comfort , power and  legs if you are eventually planning to go for longer rides, or group rides. It is inevitable that you'd be shopping for a more suitable, more powerful multi-cylinder bike soon after. Which is why there are so many used, low mileage dominars in the market as most riders will upgrade after a year or 2 for those that are financially capable.

The original crash bars actually work pretty well. I had my bike down at least 50 times, lost count years ago (going off road will do that to you) and I'm only on my second set of (ori) crash bars..and they are cheap at 25 each. The body isn't scuffed, and I still have my original mirrors. The brake lever was bent though but they are cheap to replace. Broken a foot peg but that's also cheap item to replace. Exhaust is scuffed but it's a minor issue.

The only thing that seems to get easily damaged is the gear shifter, which tends to get bent each time you drop it. I do have rear pannier racks and panniers so they do take the brunt of the impact when I go down.

Basically, parts for the dominar are cheap. So if you break them, just replace them. Which is also why it works so well as a beginner big bike.

I do my own repairs. Sometime have to macgyver shit up if your are off road and break something.

Sure, you can put a more comprehensive crash bar but at that point it just looks silly. It cost more than the usual parts that get damaged and need repairs. Full crash bars are ok if you are actually going to go off-road or stunting, where you will drop it often, but looks silly on a daily bike.

Crash bars are consumable items. Just so you know. Drop them a few times, and you may need to repair or replace them. Given how much(or little in this case) a dominar costs, it's just not worth "protecting it".

safest way is just both you and owner go to JPJ and do the transfer.