I have them on my Graf 502's. This is my first time using T-Blades. I can tell you this: there is no better feeling than having a sharpened pair of skates. I can get a month out of my T-Blades before I get a new pair. I use one of those ceramic sticks on my T-Blades, and it sharpens them nicely, but it is nice to have a brand new pair.
I'm not sure if it's just mine, but my T-Blade holder is very chinsy. I've taken a few pucks to the holder of my T-Blades, and they feel like they are falling apart.
Once I can afford a new pair of skates, I am definately switching back to my old TUUK Lightspeed holder.
So if you don't have easy access to regular skate shapening, get the T-Blades. If you do have easy access, just get a regular holder.