Keep in mind that Henderson has multiple sub-lines. The Insta-Dry is their flagship product (even if the flag is a little tattered right now). Next down is their Goldcore. I have a 3mm Goldcore full, and a 3mm Goldcore core warmer. They go on like greased ice (well, maybe not *greased* ice...), and they hold up well. I'm pleased. It's also supposed to remain a bit warmer than a standard 3mm. Much less expensive than the Insta Dry. (I *do* have Insta-Dry booties...figured booties take too long to dry, and it really *does* work for them). There's also the Titanium Hyperstretch, which most folks swear by from a comfort perspective ('specially if you're not an 'off-the-rack' fit).
I also have a 5mm Bare that adds ankle zippers and gussets, ankle and wrist glideseal, a thicker lumbar gusset, "Progressive Stretch," and was half the price of my Goldcore. Doesn't go on as easily, but it's a great suit.