I have almost always owned acrylic tanks. Yes they will scratch and yes they are a little tougher
to clean. I always clean the inside with the white filter pad you can get in bulk at the LFS and as
far a cleaning the outside I always used the plain white wash cloths you buy in a 12 pack at
Walmart. Wet one for wiping the dirt and smudges off and another one dry for polishing the tank
dry. The other drawback is if you are using MH lighting avoid placing the bulb directly over the
braces, could soften the acrylic, just a precaution. Other than that you can't beat the clarity.
I also lived in California for a while and that is all you can use in the earth quake areas because
acrylic gives and won't shatter like glass.
Just my input hope it helps.