Pinnacle Black Ice questions

[Scouter]

Hi All
Newbie here - well sorta - I got my original certification in 1974 but I have been away for a while. Now I am looking to get back into Scuba and have a lot of equipment questions. I may become a pain around here for a while - please bare with me.

I am considering a dry suit. Currently leaning towards a Pinnacle black ice or a DUI CF200 or FLX 50/50.

Comments pro and con for each would be very welcome.

Specifically are the DUI suits worth the extra $
Is the custom sizing of the DUI worth the extra $
Is the Merino lining of the black ice as nice as it sounds?
With the Merinao lining can I get by with a light weight under garment?
Should the black ice be sized to a larger under garment and what negative affects would that have if I then wore a light weight undergarment during a warmer dive?

Hey I am sorry but I am full of questions about the gear that is available now. Soooo much to decide and sooo little knowledge - Help - help- and THANK YOU for any help in advance. 

Brian