Ouch!
Might I recommend only using Differential on a daily basis (not an hourly) and backing up the Transaction Log on an hourly basis instead?
I've never seen Differentials as an "hourly" type of backup. Others may have different opinions, but Differentials, IMHO, should be used so you don't have to have a daily FULL backup if your database is large.
If I'm misunderstanding your backup plan, I apologize.