That's why I go with the neoprene for sumps and caving, drysuits are just too expensive to put through that much abuse (and that is why I don't mind finding used wetsuits for that purpose.) With the amount of lead it takes to sink me in a 7mm, I would hate to even try a 10mm. The only time I am really comfortable with 48-52 degree water is when it's in a drinking glass, but that is typically what we see in sumps and the caves up this way. I am okay in the 2 piece 7mm, but like you mentioned I stay moving the entire time and you have never seen an old cripple doff a wet wetsuit as fast as I do when I exit.