Boot time and mods, it is a tough choice for me and in the end I think the pros outweigh the boot time issue. We can mod the crap out of this unit. Custom screens, backgrounds, colors, screen layouts and what info is displayed and the grand king of them all, the software over-ride, at least for me. It is worth the extra few seconds, you can get rolling and do what you need in a block because you aren't locked out of the unit like other systems (or oems).
Yeah my OEM camry nav is on like instantly but I also have to sit and wait in the garage or driveway to program the destination because as soon as I hit 1mph I am locked out. In my civic (avic) I jump in and go and when I hit the light at the end of the block I load the destination in. So, really, I an up and going faster than I am in the other car. All in all it is prolly the same amount of time.
I bought the system because of the mod ability and it is worth it. Just my 2 cents.