Used a Tobe Rex Monosuit all last year, love it. Going from HMK pants and a High Quality FXR Coat, I find it much better. Mine is non-insulated, and I just layer accordingly - usually riding between 0 and -10 C, base layer, pants and long sleeve and a Tek vest. Usually have a hoodie or sweater in the gear bag if I end up riding late or get some nasty windchills.
Only complaint I had was a set of suspenders would have been great, especially when you are stopped and have the top half opened or down. I do see the Rex V2 has the suspenders for this year. I only found the sizing to run a little big. Even with the Tek vest, it's a little big on me. They do have a lot of great pictures to help you decide, but I could have went a size down I'd say.
I also bought mine at the end of season near 40% off, just in case you didn't need it right away.