It all depends on what you using it for, what you want to get out of it, how long long you want it to last and ultimately -how much you want to spend.
The CIR24 isnt a great gun-but its ok, one of these generic pieces. Ok for ocasional/hobby use, but dont realy on it un doing every nut you put it on. The CIR450 is worth the extra, and would give a good comprimise for you.As you would have a gun that should be upto the jobs and for hobby use, id imagine it would last you a long time.
But it still isnt the best for out and out professional use, where you may spend double that again. But thats alot of money to have laying around for hobby use in my opinion.