The old Merino-Elastirprene suits are excellent, with full coverage of the interior in the merino wool material creating great insulation in a thin suit (my 7mm ME suit was a hell of a lot warmer than even a properly fitted 7mm farmer john, and my 3mm ME suit worked great in water most people liked a 5mm or 7mm for). They also ran a little small: I'm a large in a Pinnacle M-E suit, but a Medium-Tall in their current version of the same suit (Tempo).
The new ones, marketed as the Tempo, are not fully merino lined but instead have a lot of the interior covered in a similarly blue but not wool lining material that sucks. The new model's zippers are also crappy plastic instead of the heavy duty YKK marine brass used on the old ME version. I'll try not to dwell on the fabulous new color scheme that replaced the great black/charcoal coloring on the ME series. Basically, the only thing they improved about the suit was the match between the size chart and their suits' actual sizing.
As far as I can tell, Pinnacle built a reputation on quality based in large part on the merino lining, and then tried to make $$$ by charging the same prices for poorly designed 'upgraded' suits that weren't as fully wool lined as before. Buy and love the old ones if you can find them, but avoid the new ones like the plague they are.