This is a bit similar to my current thinking...
Currently I have a Brera 2.4, but I'm just not enjoying as much as I hoped. It's a 2006, so there's no power until well over 2,000rpm and it just feels too lumpy in terms of power delivery. I had a 147 1.9, and I never had to work it as hard, and diesels just don't feel the same as a petrol when driving that way. Dynamically, it's also way off my GTV (previous car).
Therefore, I am thinking V6 - I can probably get away with fuel bills (just), as I do around 10K per year up and down the A3. I think Brera, as the looks are just stunning I don't think anything else gets close.
But...the v6 of the GTAs or GTs appeal in terms of fun. Lighter cars, and probably more room in the back (not essential but helpful). The fear is an older car (or design) and bigger bills with worse reliability, but that can happen anyway and the Brera hasn't been perfect.
I think a few test drives are needed, but is the Busso V6 (and associated mechanicals) much worse to look after than the Brera version?