I've had mine for a couple of years now and love it. I wear it in the course and free skiing.
Deep water starts took a little while to get down, but it's an adjustment, not a major technique change. As others stated, "let the vest do the work".
I have the straps adjusted so only at full arm reach do they just engage. I find this works as it allows me to use mostly my arms to get up, but once I'm skiing, the vest does a lot of the work.
As a chronic lower back pain sufferer, I applaud Dave on this design. And, I should add, great support from them. One of my gloves broke last season, at the d-ring, and I received a new pair over-nite. Good people, great product, IMHO.