I know this thread was started a long time ago, but in case anyone else is interested, I own Terrapin Wetsuits, and we do zipper repairs, alterations, and custom wetsuits. I ALWAYS recommend a front zipper for scuba diving wetsuits (not for surfing). The reasons are many:
1) Neoprene stretches and zippers don't, so if your zipper is in the back, all the stretch from sitting, bending, etc... happens in that short space between the bottom of the zipper and the crotch seam, so the suit will wear out quickly in this area.
2) To allow for some stretch to happen, mass-manufactured suits have shorter area for the zipper in the back so they typicallly put in an 18" or shorter zipper (compared to a 22" or longer area for a front zipper). The longer the zipper, the easier it is to get in/out of the suit.
3) Pulling the pull cord too fast on a fully-opened back zipper can cause the zlider to catch on the flap under the zipper teeth. If you don't know that's happened, and jerk it some more, you may either tear the flap, or pull the slider completely off. While both are fixable, this hardly every happens on a front zip suit.
If you have trouble getting in/out of your back-zip suit, Terrapin Wetsuits can add a front zipper to an existing suit, so you can use both to open the suit and make doffing very easy.
Cheers, Chris Summers