I may be able to offer some help.
I've run a GT4 for approaching 7 years. In that time it has let me down just once... that being a dead battery due to the age of it. Basically, it has been the most reliable car (or any kind) I have ever owned.
Ah, is it pampered I hear you ask? Far from it. I've spanked it round the Top Gear track three times, Brands GP circuit twice, Sneterton, North Weald etc etc. OK, the throttle stuck open going down Hawthorn, but not the cars fault!
Like you, I have offspring who occasionaly want to go out in the car too, or more accurately we can go out as a family of four in the GT4 rather than using the Audi estate. Some pics below of this and the various car shows, events, track days and even Italian Day at the kids school that I brought the car in for.
I occasionally use it for work (80 mile round trip) and it's fine. No real agro from other road users which I think is partly because it's not as "obvious" as a 308 GTB/S.
There's a fella called Nick on ferrarichat who used his as his daily car for a few years with no negative outcomes.
If you get one, make sure the drivers seat is in good condition and have re-stuffed if needed as they get a little thin over the years. I have 16" wheels on mine which has transformed the handling, improved grip and made the steering lighter!
In a word.... go for it.
Any questions, just ask.