I feel like increasing it based on the number of 50's would be a hand-out. Even if I had all 50's I would be fine with just the 450 increase. With CT and Coil in addition to 450 tomes, you're at least getting 2-3+ pieces of i80-90 gear a week (1 from tower, 1 from myth, anywhere from 1-4 from coil).. and that's more than fair in my eyes.

That's just my opinion though. So /shrug