Weezles are controversial.
I dive an Extreme+ in Puget Sound. IMHO it's a tad much for most of the east coast below Virginia Beach or Nags Head, though, unless you get to depths below 200' off Ocean City, MD or points north occasionally.
Pros:
Real warm. I've not found anything warmer...
Cons:
Weezle's don't stretch. Dive'em tight and you may have issues with valve drills.
Weezle's require loft. Consequently, you will typically use more gas in your suit than when using a thinsulate garment. Ergo, you will require more weight.
Weezles are not DIR if this is something you're tracking. The additional gas inside the suit makes bouyancy and trim less stable, as it moves about inside the suit when the diver's attitude in the water column changes. One claim is that reflective technologies provide equal thermal protection with less gas inside the suit. Less gas in the suit is true. 'Equal thermal protection' is a subjective determination.
Controversies:
#1 Flooded drysuit. Claim: "If you flood a drysuit in extremely cold water with a deco obligation, a thinsulate (e.g. 'reflective' technology) garment will still keep you warm whereas a loft undergarment will lose all thermal protective properties." Hence thinsulate is superior to Weezle.
Doc's opinion: If you flood a drysuit in 30-40 degree (F) water with a hefty deco obligation remaining, you're going to be a miserable unit regardless of which undergarment you're wearing. I have seen zero research - no empirical evidence - suggesting any measurable or quantifiable difference between a thinsulate garment and a weezle under such circumstances. [That doesn't mean there isn't any, it means if there is I'm unaware of it.]
#2 Fabric obstructing drysuit valve. Claim: "Nylon fabric used in Weezles has been sucked into the slots on the inner face of the drysuit purge valve, thereby preventing the discharge of gas and causing or exacerbating an out-of-control ascent."
Doc's opinion: I've seen photos from one diver who claims this occurred to him. The photos would tend to support the claim. The extent to which any other issues contributed to the incident are unknown. The diver is reliable and experienced. I'm also aware of another case where it is alleged that something like this may have occurred. It was a fatality, the reports (that I've read) do not offer sufficient detail to reach any informed conclusion. Possibly true. Bottom line is that many divers use Weezles and do not have this occur to them. Also, putting something like a fabric patch on your undergarment beneath where it contacts the shoulder dump valve would seem to be a fairly low-cost insurance policy against such an occurrence.
So for extremely cold water diving, Weezle's do a superior job of keeping a diver warm.
They bring other things to the table that you may want to think about, but they will undeniably keep you warm. Hope this helps.
Doc
