+1 for buoyancy control and water comfort.
As far as BCD's are concerned I love my Halcyon Infinity system with cinch harness and would replace it with the same in a heartbeat. The "cinch" system is an adjustable single webbing system that allows for ease of getting into and out of your kit, pretty much instant resizing for wetsuit to drysuit without the need for any extraneous clips and buckles. Have someone who knows how to set it up help you get it dialed because a crappy fitting backplate and wing can be as bad as anything else that doesn't fit.
If you are small stature, they have a short plate, and if you travel or need more flexibility in weighting, they have an aluminum version.
The bottom line for me is getting kit that 'just works' when it comes to gear, i don't want to have to think about it underwater, I want it to blend into the background so I can focus on the shot. I do my part (maintenance) and it does its part (just works). With regards to sealed, are you diving in excessively cold water? If not, don't worry about it. I've been diving in Puget Sound and surrounding lakes for 25 years and have never had a reg freeze on me (knock on wood).