Good questions. I can tell you about December.

Not sure if I will need less weight or not. I wear a 3 mil suit and in the past 16-18# of lead. Tried on the suit a while back and think I can still wear it but will put a one mil vest underneath it to fill out where the fat used to be. The suit was stretched a lot before. Now it will actually fit more like it should.

So with the extra vest underneath, I'm guessing maybe the weight in the weight pouches might not change much. The vest should give me a little more warmth also. Where we dive December through mid March the water temperature is usually around 79-82. Some people don't even wear wetsuits, but our dives are rarely under an hour and up to an hour and a half. Typical is 1:15. So the latter half of the dive we would get pretty cold if not for the suits. Sure would be nice to drop a few pounds of lead.

I would surely hope I would use less air, but air is never a problem anyway. My wife puts air back into the tank I think. She did a two hour dive on a 50 cu ft tank once (in only 15' of water). Not a 60, but a 50.  I did the same dive on an 80. We were mostly just laying on the bottom watching small critters so no exertion. She still had a little air left. I was sucking fumes. I'll do 135' for just a few minutes and still have over an hour dive with the rest of it at 30-50. I'm pretty comfortable under water. Wife always dives a 60 in Bonaire, will do more than an hour dive, and is disappointed and worried about her air consumption if she hits the dock with less than a thousand. LOL.

John