Not necessarily ... many of those who dive drysuit regularly can "go head down" at will. You just have to manage the air in your suit ... which usually means not using your drysuit for buoyancy control, and only keeping adequate air in the suit to loft the undergarment. With some practice you can orient yourself in any position you choose to in a drysuit without difficulty.
... Bob (Grateful Diver)
A friend of mine showed this very aptly on a dive we did a couple of years ago. He is an incredibly creative person... One of those people who makes comments you never expect but that hit the nail right on the head..... one of those people who sees the world the way it is, not the way you want it to be. He's not a rule follower (duh) which makes him a good buddy for me because he shows me boundaries that, as a slightly autistic control freak, I don't dare to test.
So we were diving in a Belgian quarry and there was a pipe stood end-up on the bottom from about 20 to about 8 metres. It was intended for a swim through. There was a hole in the bottom. Sven (that's his name) signed to me, "watch this" and he went into the pipe upside down and backwards (feet first) at the deep end in a drysuit. I figured he would come out the top of it bloated and out of control so I went up the outside of the pipe to the top to catch him. He did come out of the top of the pipe bloated with "elephant" legs but the moment his head cleared the pipe he rolled and vented and only ascended about another metre or so before he stopped and ended horizontal and in control.
That's an inverted ascent over 12 meters that he stopped within 1 meter of depth.
As an aside, a little later in the dive I lost him. I swum under a platform that was hung well over the bottom at 5m depth. I looked left and right and didn't see him so I looked over my head and saw him upside down doing a Michael Jackson "moon walk" across the under side of the platform.
As another aside, he was a hard-core DIR diver who eventually turned his back to DIR. This puzzled me because I am a hard core DIR curious technical diver who has never been able to let go of the fact that I am not 100% DIR. What he said to me says a lot about him, but also about me and about DIR. He said, "I got tired of talking intelligently about diving, and just wanted to go diving".
That said, there is a reason why he was able to stop a 12m inverted ascent so quickly.....
R..