I've had both. My first pair were the SIDI Vertigo's. Really liked them and they were my road boot.
When I started getting into riding the track, I found a pair of A*'s SMX- Plus. While both are very comparable, I found the SMX-Plus to be a little more comfortable. The inner lacing system on the SMX-Plus is the key to the whole equation in my opinion. Bar none, I could wear my SMX-Plus all day and never have a problem.
As far as sole's wearing out...
Racers tend to wear soles the most in the area just behind the toes (the "front ball"). If you are just casually riding (not in a hard-core racing stance) with your foot square on the peg, I would guess that wear would be the same. If you do a lot of walking, that could contribute as well but I'm not sure on wear amounts from manufacture to manufacture or model to model.
In short you absolutley won't go wrong with a Sidi or A*s boot. It's ultimately going to come down to fit, features and price. I had my Sidi's and they were wonderful. I also love my A*s and can't imagine doing track riding that I do in any other boot.
Just my $0.13 (adjusted for inflation)
'Dee'