Picked up a Lavacore full suit at my LDS a couple weeks ago. On Friday I dove my drysuit for the first dive and decided it was too warm. Put on the Lavacore, adjusted weights, and went for a dip. The suit is essentially 5mm worth of neoprene insulation in a 3mm or less package. I wore it in 60F water with a 5mm hood and 5mm gloves without feeling cold. I wouldn't spend 2 hours there, but for the 20 minutes I was at that depth, it wasn't bad. My general rule of thumb is "motorcycle cold". Basically, if it's a felt temp I can ride my bike at and be comfortable, I can dive it. I did dive it down to temps around 50 and managed to stay about 3 minutes before the pain started. At $219 MSRP, you can't beat it.