I'm not sure there is such thing as 'DIR-Compliant' drysuits. But there are going to be some characteristics that support the philosophy. The three primary ones that come to mind will be: pockets, fit, and color
That said, there are few desirable things to keep in mind:
Shell suit or neoprene? Neoprene compresses and changes buoyancy characteristics with depth. A good shell suit is constant-buoyancy. Though with crushed neoprene you can eliminate buoyancy shifts. Some colder environments will demand neoprene, otherwise stick with a good shell suit. The Waterproof D7 is a shell cordura shell suit, much like that Bare Trilam HD tech and DUI CLX 450 is cordura. Weight and time to dry could be a concern if you travel. Neoprene takes the longest to dry and is heavy. Trilam tends to be light and quick to dry. Cordura somewhere in the middle but is also quite durable.
Proper fit. Using the thickest under-G the fit should be not too snug but not a lot of excess slack. At the knees you'll want some slack (an inch or two) to support the prone position and and long enough arms to support valve manipulation but not much more than that. The only way to know for sure is to try it. I've tried many that on paper appear to support my size and shape but in fact do not have proper fit characteristics. If it's too tight it'll be restrictive, uncomfortable, and may put stress on the seems.
Zippers. Front entry is best, then you can self-don. I've heard someone complain that back-entry zippers could wear faster but I don't have any way to substantiate that. Also look for a zipper guard to protect the main zipper. These come in the form of another zipper that zips over the main to protect it, or velcro flap. The WPD7 has this on covered.
Pockets. For DIR diving pockets are a near must. You can store your backup mast, safety spool, SMB, wetnotes, or whatever else without it becoming a snag-hazzard. Prefer a way to attach a bungee (as wide as the pocket or a large enough loop so you can blindly attach a bolt-snap quickly) so you can clip off the items in your pocket. Some pockets are zipper, some are velcro. Some are both. For opening closing the cargo bin, prefer velco. I haven't used zipper pockets but I have used zipper weight belts/pouches and sand or kelp can jam up the zipper not to mention the teethe can fail and jam you up also. Some pockets like the DUI cargos and Halcyons are velro to the cargo bin and zipper sub-pockets. The UTD pockets used zippers to control space but velcro otherwise, when zipped for smaller cargo bin, unzipped for larger cargo bin. The WPD7 seems to be a velcro bin, can't tell for sure though. It's listed as expandable so may be the UTD style.
Padding. Additional protection in high-wear areas which could be the elbows, knees, or crotch (for scootering). Seems that WP D7 has this one covered.
Boots. This is subjective. I doubt there's a DIR policy on this. Personally, I like boots. My Fusion has semi-attached boots that I can change out but they're attached by velcro. For the DUI, I tested and preferd the rock boots (I can change them out and can keep my fins). Tried the turbo soles and didn't like them, wife had issues with them, too. But the boots aren't attached and can be forgotten. But so can the depth guage. The WPD7 seems to use the sock & boot approach. Do what works for you although the decision has been made already in the case of the WPD7 suit.
Seals. User-replaceble introduces fail points but trades off with speed to fix. During my cave class, a student and instructor experienced neckseal tears and were out that drysuit for days during class. With replaceble system only minutes would have been lost. I've never had a problem with latex seals in my SiTec locking system, but never had success with silicone ones. The WPD7 comes with silicone but I'm sure you can use latex. Personally, I'd prefer to have a field replaceble system which helps prevent lost dives on trips or expeditions. WPD7 appears to use the SiTec system (that I have). I cannot comment to the neck seal system whether its any good or not.
Color: has to be all black or with red overlays :d The W7 has some red. It's actually a slick looking suit.
P-Valve. If you don't have one, then a front-entry is all the better. But gotta have one of these. The WPD7 doesn't have one listed as default option.
I may have missed something, this is just off the top of my head.
