Brother HL-3170CDW vs HL-4150CDN

Hi,
I am ready to retire my HP Color Laser 2605dn that is in need of another
cleaning and toner cartridge package. I am thinking that the $300 that will
cost can be put into either a new Brother HL-3170CDW or a HL-4150CDN. I like
the 4150 because of the higher capacity toner cartridges and print speed but
have questions.

a) Is clinging to the older laser technology a mistake? From what I have
been reading the LED technology used in the 3170 is good but the 4150s laser
gives better quality and speed.

b) I print single envelopes occasionally and am confused by the 4150
description of the procedure. Is the envelope ejected from the front or
rear? The rear of the printer will not be accessible without great
difficulty.

c) It looks like the Brother Web site has up-to-date software for my OS,
Windows 7 64-bit. I have been using PLC 6 with the 2605 since Windows Vista
and am used to the reduced features compared to host based drivers.

Comments please... Dean