Looks like I need to do some more looking - Weezle and 4th Element added (gotta take into effect which MFG's I can get a keyman on - so the end price/value). I've had no issues when my fleece gets wet. I'm just leery of Thinsulate because of the washing issue. I'm a lazy a$$ and whatever I can just toss in the washer and hang or put in the dryer is best. I want LOW maintenance. Thanks all for the suggestions!
I'm also looking for a warmer undergarment than my single layer fleece, as I'll be getting into tech diving with deco hangs. So it needs to have something other than fleece in case the suit floods.
I liked the Weezle when I tried it on, although I need the Med Long or I'd rip the underarm seam out in short order when putting my drysuit on; haven't had a chance to try one diving. The only negative I've heard is that the Weezle can block the exhaust valve by surrounding it; some people have suggested sticking a piece of duct tape on the upper left arm of the Weezle to prevent this. The only other problem I have with them is that the pocket openings are on the side seams. Great for your posture, but I suspect I'd rip out the stitching at the corners of the pocket entrances in no time. The material appears to be very light Pertex; great for weight saving on sleeping bags, but I confess to being worried about its long-term durability in this application. Others who've owned one for a while can give it a thumb up or down on that score.
I tried the White's Mk.2 (100?g fleece) and Mk.3 (100?g fleece and ?g Primaloft) Johns last weekend. I froze in the Mk.2 over a REI LS Zip-T and polyester swim suit in 53 deg., but that was under a Fusion instead of my own CF-200. The Mk.2 John can't possibly be less warm than the single layer Parkway fleece I'm using now.
Realistically, you'd need to wear the Mk.2 John over the Mk.1, or the Mk.2 Jacket (w/wo sleeves) over the Mk.2 John in these conditions under a tri-lam suit, and especially under 50 deg. I wish that the Mk.2 John had nylon covering the entire fleece. The front of the thighs and the lower back below the shoulders leave the fleece exposed, which decreases its usefulness as an outergarment in cold and windy conditions during an SI.
I tried the Mk.3 (same base layer) in my CF200 the next day, and was toasty warm doing a 77 min. surveying dive in 51 deg. water, i.e. short stints of swimming followed by several minutes of recording data; I'm looking for an undergarment for deco hangs in 40-50 deg., and the Mk.3 would seem to allow that. Unlike the Mk.2, it has a complete nylon outer shell.
The Whites' have the best designed pockets I've yet seen, with handwarmer pockets up above the waist so you can use them when you've got your drysuit pulled down, and two chest stash pockets with vertical zippers either side of the main zipper, so you can actually get into them (if you have a drysuit with a diagonal cross chest zip) without having to take your head out of the neck seal. And the drop seat means you don't have to remove the undergarment or else dump it onto a wet bathroom floor, if you have to sit on the throne. Both of them appear to be rugged enough to stand up to dive treatment, and the Primaloft may be a bit easier to take care of than Thinsulate, although both are short-staple fibers.
The Mk.3 is a bit restrictive compared to the single layer fleece I'm used to (not surprising), but by reputation is a lot more flexible than a DUI 400g; I don't know how it stacks up against the XM450. I (6', 175-180 lb.) could really use a size ML or M Tall, but unfortunately my options are M or L. The lack of a vent in the upper arm of the Mk.2 and Mk.3 makes them (esp. the Mk.3) a bit slow to vent, although on the Mk.2 you could always unzip the left sleeve slightly.
I've read good things about the Fourth Element stuff, and being two piece it eliminates a lot of the bathroom issues that the drop seat on the Whites are designed to solve. But IIRR, except for the SubX you need a separate wind layer over it for the SI.
I know someone who has the Pinnacle Merino Evolution undergarment, and he seems to be reasonably warm in sub-50 deg. water despite being a photographer and a smoker. He wears it over a Helly Hansen two-piece base layer. I won't buy one because they've got a rib-knit collar, which is hell on my neck. I want a fleece collar, or nylon over insulation like the Weezle.
Finally, Hollis appears to be trying to aggressively enter the market by undercutting everyone on price; I've seen their AUG200 (100g fleece and 200g Thinsulate) for $185 or less etail, which is way under everyone else. They also have vent panels in the left sleeve, one in the upper arm and one at the wrist, so they should vent pretty well. I just need to find one to try on, but I'm only 10 minutes or so from their/Oceanic's headquarters so should manage.
EDIT: I see now that Hollis is saying that the AUG 200 insulation is 200g technical fleece. I could have sworn that the 2009 catalog I have gives the fleece/thinsulate combo above, but will check. OTOH, that same catalog says it's available in ML, but their online catalog doesn't list that size. If it's just fleece, that would explain the low price.
Add: Okay, I checked the catalog and it does say it's 200g Thinsulate over 100g fleece, and I found an SB post from 2008 by the owner? HollisNick who so states. So either they've changed it to 200g fleece, or the online catalog and dealer writeup is in error.
HTH,
Guy
It hold me easily warm for 45min in 0-4C waters 
