I am thinking of making the switch from a jacket style BC to a bp/w system. But I have some concerns. I'm debating if I should go for an aluminum or steel backplate. As of right now, I only need 6lbs of weight to sink with an AL 80 and a wetsuit (3mm). If I were to get a steel backplate, I effectively, would not need any weight when I'm diving in warm water, and would need less weight when I make the switch to cold water (and possibly steel tanks as well). My concern is that I will be a bit overweighted in warm water. So would an aluminum back plate be a better option (I can only afford one back plate right now)? Also, I'm on the small side (5'3, 125 lbs). How would I size the backplate? Any suggestions on where to look?