Yeah, I do have 2 whatsapp account, on ios and android.
In term of hang, ios won't fail you. My SE mainly for testing purpose, so I use the most used app on Android, onto Ios.
If on ios9, you will feel some lagginess each time you open your Whatsapp, like the app try to connect to internet.
On ios10, Apple removed the loading bar, making you feel Whatsapp working as fast as you're opening the app.

Bear in mind, if you're migrating Whatsapp data from Android to IOS, you might need to use paid app, which will cost not cheap.
I forgot what the app called. Backuptrans something like that.

That's normal, maybe unethic but still normal. Because to secure an unit before buyer come rush in to buy on launch day, and also to standby more unit.
Plus to avoid buyer only survey at their store and buy from somewhere else later.

I'd reject such offer as so called pay deposit to secure your unit.

I paid rm50 to secure ip6s rose gold on launching day, at Digi Centre, for waiting MNP process to success which was need up to 48 hours. The amount will be deducted on the phone price.

Well there's almost no risk, unless you've never go back to the store. If MNP fail, they refund the deposit, if you cancel order also they refund your deposit. It just they need you to come back for your money, and to know why you'd cancel the order. They can't keep the deposit if the purchase not proceed.

If they still refuse to give back the money, you can always log police report. Make sure to get proof of deposit payment.

Well, it's good for you to win anything, but here isn't really place for you to sell anything.

oo..ios can clear ram? this is new