I have the Henderson 7/5mm Semi-dry. I am a real lightweight when it comes to cold, still, I can wear it all by itself down to 58-60 degree F surface temperatures. At that I'll begin to feel a little chilled after 50 minutes of BT.
If I add a 5mm Gold Core core warmer, I have dove it in 47 degree F water. At this, my body was great, not a hint of chill, but my hands (in 5mm velcro cuff gloves) ended up pretty cold. I have heard that a pair of 6.5mm Gold Core gloves with the cuffs folded under the suit sleeves fixes this.
The suit definitely has less than one water exchange, so say goodby to peeing in your wetsuit.
A very nice feature is the Hyperstretch shoulders, quite flexible and you still get the advantage of Gold Core.
The only problem...this is a custom suit. It took 9 (nine) months to get it made, and then the fit was waaay wrong. After one alteration, it still needs work. If I need another custom semi-dry, I will go elsewhere.
All the best, James