VoIP on IOS 4.0 experiences?

[lifespeed]

OK, it may be a little early. But 4.0 is out now, at least unofficially. I've got a copy but haven't installed it, reason being I really need VoIP to work.

I have a jailbroken 3GS with 3.01 FW. Using Siphon, Insomnia, Backgrounder AND a mod to the a plist file to keep the wifi from shutting down after half an hour I finally got it to work 98% reliably. Every once in a great while it will fail to remain connected to the VoIP server, but this is rare.

So, after a ridiculous amount of work to make it happen Against Apple's Will, I am slightly concerned about ditching my reliable setup for IOS 4.0 and the promised native VoIP. But it could be 100% reliable instead of 98% if they actually intended for it to work.

Has anybody use VoIP with iOS 4.0 on a 3GS over wifi? Was it reliable?