Are you familiar with the Seaskin neoprene, or are just referring to neoprene suits in general?
The Seaskin neoprene is 3 mil crushed. Mine dries overnight with a fan easily. What do you mean exactly by the shell has more "flexibility" ? People often make these comments on Scubaboard, but I haven't been really convinced of the supposed superiority of shell suits. Especially if you were to get flooded, a neoprene suit will provide more warmth in this case as compared to a shell.
If you have the money, feel free to go with replaceable neck and wrist seals, but be aware that they cost a serious chunk of change (increasing the suit price by about 50%?). Also, neoprene seals are really robust, can be field-repaired if required, and also provide warmth, compared to silicone. For me, it wasn't worth the huge price difference. If my seal gets damaged, i'll send it off for repairs; I don't dive enough for a couple week delay to really hurt me that much.
Agreed with the socks over integrated boots.
We may need to agree to disagree. . . my shell suit can be inverted and completely dried with a towel in < 1 minute.
As for flexibility, 3 mm vs 1.3 mm (a SWAG on my trilam shell thickness)
Finally SiTech replaceable seals aren't really that expensive. About $170 for both neck and wrist when (again not if) I rip a seal, I can make the repair on the diveboat in < 5 minutes. Plus they let you use silicone seals if you choose. (SiTech must be much more expensive in Japan).