On the Pirelli, honestly, it's what I've always run on it and I have a comfort level with, though I've also used the Metzeler TD Slick and I couldn't tell much of a difference. My Daytona is my 'A' bike that I'm using to build my skills on and I don't want to mix things up too much. The N400 (my 'B' bike and kart track bike), I use the Dunlops because my coach has encouraged those tires (specifically the 160 rear because with the stock suspension it gives it the right geometry). On that bike they also work well because of the stiffer carcass because the stock suspension is so soft.
On the Tuono, I will try a set of Q5s once I use up the OEM Super Corsas though I suspect I'll end up with the Rosso IV unless the Q5 amazes me. I think I'm just generally biased toward Pirelli for no real reason.
Spare wheels? Yeah, as I improve I'm finding I'm going through tires dramatically faster. I have spare wheels for all 3 of my bikes, in fact 2 spare rears for the Daytona. I even just added a captive rear caliper and quick change setup for it. Just a few seconds improvement becomes dramatically more expensive, but it's worth it.