Telex 750 suck for the RJ. There's better out there. Don't waste your money on them. Most Telex 750 wearers also have earplugs in; makes no freakin sense. A good pair of ANRs for jets work great. You won't regret the money you spent. And don't ever wear the headsets that you wore when you were instructing or flying freight in that noisey turboprop!
Take a look at the "AURI COM" headset made by Quiet Technologies. It's very light weight, has a speaker in both ears and doesn't give you the ole headset head. You can use a molded ear plug that cuts out airplane niose but with a small hole in the middle allows full volume radio reception. www.Quiettechnologies.com. Great product!
I've tried what seems like everything. I've used the Sennheiser HMEC25's and they work great. No ANR is needed with them but it's still a clamp after a while on your head. I also tried the Telex 750's with earplugs and didn't like that too much. Then I went for the Telex 850's and they are very comfortable but I thought the sound quality was aweful. It may have just been the pair that I had though. Finally I'm using molded earpieces in both ears with a Telex 5X5. Works great IMO.