Fine printer if you don't do envelopes

I am an in-house computer tech for a non-profit company. I have been buying HL-5250DN's because HP laser printers with networking built-in are overpriced. All my installations until now have been in offices with 1 to 4 people using the printer.

Today I replaced an HP Laserjet 2100TN with this Brother because a replacement HP printer with networking built in was going to cost $500. Before the day was out I got a call that it wrinkles envelopes. After experimenting with the printer I installed today AND three other 5250's in the same building, I can say with confidence these suck at printing envelopes. After no luck with company pre-printed envelopes, I tried plain white #10 in two brands. Out of four 5250's, I could not get one envelope to print without some sort of wrinkling... the company envelopes were really bad, the plain white not so much but still noticeable.

Other than that, these printers have done well although I don't think any of my users have tried the duplex option. They have always sounded like they want to eat paper which bothered me at first but they haven't actually done it so I stopped worrying about the sound the paper makes as it goes through the feed rollers.