I have an Axim x51v with the Widcomm BT driver hack and iGuidance has always worked.
There isn't much difference between the two drivers as far as computability goes. That doesn't mean all things with work on both, nor does it mean that both will offer the same service.
Personally I think Widcomm drivers would be more universally supported as Widcomm has the majority of the chips out there. MS drivers are semi-new.
Basically, don't worry about it. Widcomm can do everything MS can do, only better.
I just installed the WIDCOMM drivers on my X51v (A12). I am definitely having problems with iGuidance and the WIDCOMM drives. I had the same problem before, but thought it was due to a bloated system. iGuidance doesn't see the GPS, even though it's properly paired.
I have no problems with the Microsoft stack. Sucks, too, since I wanted to use my BT headset with my axim. :(
Works fine with a factory installed Widcomm stack. Don't know about one that's installed on a unit which came with the MS stack as I don't have any experience with that.
I have iGuidance and the Widcomm stack. This is what I do when I want to use the GPS. I turn on the GPS unit. I think turn on BT on the Axim, then go into Bluetooth manager, click and hold the GPS icon for the paired device and tap connect. You can verify the connection by checking active connections. Once the connection is good, I start iGuidance.
The first time you may have to set iGuidance to auto detect your GPS Unit. Also you may want to look in the widcomm thread concerning some changes in COM ports, this may help.