Ducky Shine 3 ka?

As long as the keyboard working perfectly, then is good enough.
Simple advice.

Guys. I am using ducky shine 3 now thinking about upgrading to shine 4, is it a good upgrade?

Do you do calculations often?

this keyboard you looking at is not cherry mx switches unless is the older version.they start making their own switches.

When you use full layout, you have to open your hands wide open like a bear. Using a TKL, it's actually more comfortable because your right hand don't have to stretch out too much

Newer generations KEYCOOL are all using Kailh Mechanical Switches if I am not wrong.

But, I think Kailh is quite OK too. It's very budget friendly. 

Multimedia you mean like adjusting volume? If it's this feature, Ducky keyboards have these functions too. You just need to press Fn + "Specific Key". And, some Ducky Keyboards do have extra macro keys for Calculator, Email, My Computer, etc.
RM 350 budget?
I'll recommend Ducky Zero Shine to you. Solid quality and durability with nice LEDs. 

I think by factory keyboard they mean "A keyboard which ready to use when purchased".
By Custom Keyboard, I think they mean a keyboard which being constructed manually part by part by yourself.

DAS keyboard is one of the best around. Would recommend it. But, it lacks LED. Take note for this. If you don't care about LED, you can go for it.

Still, I'll pick Ducky, Filco and CM Storm over DAS. They have a more general layout which is good for modification later if needed.

Razer is bad even with Cherry MX(their current or newer generations are Kailh).

That Ducky Shine 4.

Poker 2 has volume up down, and mute function

[attachmentid=4339238]

You meant something like this ? Honestly I still prefer using Cherry MX. This Tesoro keyboard I'm using the W key got problem, keep double output or maybe triple.

Kailh Switches, that's a known problem I guess.
My previous Razer Blackwidow Ultimate Chroma is using Razer Switches(Made by Kailh), and, I have several keys double-tapping(double output) problem too.    Though, I sent it to Warranty/RMA, and they instantly give me 1-on-1 exchange. 

The difference of feeling for Kailh and Cherry MX is minimal. I don't feel there's a huge gap of difference between them. But, quality, you're talking about Germany vs China. LOL.

Other than this, I also found out the feeling and actuation point of my Ducky Shine 4 and Filco Majestouch 2 TKL is different. Both of them are using Cherry MX Blue Switches.

yes u can. personally i think filco build is much studier compare to ducky which makes the feeling differ slightly.

i got ds3 then filco.

now collecting sums for korean. need to try.

Would definitely NOT recommend Non-Standard Layout MKB.
Simply not good for many reasons.
The main one will be keycaps choices.

I would recommend CM Storm Quickfire Rapid-i over it. Very good quality and layout and nice lighting effects! 

Filco, Topre(Realforce, meh, they're mostly not Cherry MX keycaps compatible LOL, but the layout is standard), CM Storm(in some models) and Ducky(in most models) usually have more traditional layout aka the standard layout compared to Corsair, Logitech, etc.

NOT all mechanical keyboards are using standard layout. There's a lot of them using their own layouts.
For instances(special layout):
CM Storm Quickfire TK
Corsair K95
Corsair K70
Madcatz STRIKE 7 or 5, etc
Logitech G710+

Due to their own special layouts, that'll mean there's no much compatibility for 3rd party keycaps set to put in.
Imagine, if some keys are broken, or the keycaps worn off or become shinny. You can't replace them.

CM quickfire isn't standard layout.
CM quickfire rapid-i is standard.