Sounds like a dive spot I must check out while its still COLD, water that is! Now if I could just order a warmer day with the sun out, the water temps are as big an issue when preped for it. Sounds like a trek well spent and something different with the old and new dam to check out. I have heard the drop between the 2 is at it's deepest around 100ffw. Not a sidemount guy myself much, never gave thought to swaping out the regs just about the time you got one warmed up and that cold water that little leaks in the mask/hood during the swaps--Brrrrr,,you expect it on deco's in cold water but at least your more mentally ready--lol ! Thanks for the complete report and am glad you worked thru you guys issues and got to dive. I helped a son move from our home into a 3rd. floor apt.,dang that was torture, particulary after just yesreday helping another one of my sons finish paneling his garage......that COLD water sounds pretty good compared to those 32 steps up to the 3rd. floor caring furniture. 
