I think @wigglyamp has moved on or maybe nobody flying in the UK with a GI275 who has tested this aspect. And any garmin dealer who knows the answer won’t be posting it unless it is affirmative.
This is another approach:
I’m still lurking😉
The GI275 does use pitot-aiding as well as GPS. I’ve recently done practical testing of this on a fast jet and seen the failure modes. Loss of GPS does not affect attitude provide pitot remains available and IAS is below 425 knots. Above 425 kts and with GPS lost, the attitude will coast (gradually degrade) and will indicate failure and go into realign after about 6 minutes.
Loss of GPS does not affect attitude provide pitot remains available
That’s the exact issue though, isn’t it?