I just bought and tried a Spetton Hexskin. It is actually closer to a 3mm than 2.5mm so keep this in mind if your thinking of getting one. I guess they add a little more thickness because a blind stitch would show if it were exactly 2.5mm so a little more thickness allows it to be truly blind. Another thing to note is the sizing chart on website only applies to the other suits and the Hexskin suits run a FULL size smaller. I am 6ft and 180-185 and the Medium fits me just perfect the size up was way too big which is what the chart said I needed. I talked to Paublo at Spetton USA and he said it is because they are made at a different factory and from a different cut therefore the size difference on the chart.
My overall impression: Great suit, feels like butter on my skin. Its softness is very nice and also keeps me very warm. The down side is you must take care when putting it on otherwise it can easily tear. I personally like a softer rubber that can tear rather than a stiffer rubber that lasts longer. Its all preference though.
BTW I am not affiliated with Spetton or any other manufacture. I am only a consumer and my other primary wetsuits for SoCal (5mm and 7mm) are actually Omer.