I started out, maybe six or seven years ago, with a 3ml surf suit and a Scubapro jacket with hood attatched and zip front. Water entered the suit as soon as I entered the water and in the early part of the year I'd be shaking with cold after 45 minutes.
I've had three spearo suits since, and still have all three. First was a Picasso "Apnos". This was-is open cell inside, 7ml and seemed like medium density and was warm.It got fingernail damage easily but was tough otherwise and did repair and patch easily when damaged. I was 11.5 stone when I used it and it's too tight now but still serviceable, though patched on the crotch where my weightbelt retainer rubbed it. It was size "52".
Next was a Picasso "Ghost Termic" Made of 7ml "yamamoto 45" neoprene. It was size "54" and although very warm, I had to take in the back seam of the trousers a little for a better fit. The soft "yamamoto 45" damages quite easily on the inside.
My present suit is an Elios made to measure 5ml "Heiwa medium density" camo nylon outside, "newblack" (a closed cell finish) inside. Its warm, comfortable, fits perfectly and seems reasonably tough.
In winter I'll probably switch jackets back to the 7ml "Ghost Termic", but not until I have to, as the soft neoprene compresses on dives and you either feel heavy at depth, or have trouble leaving the surface, depending on how much weight you wear.
I think you probably remember the old nylon inside suits as warm because you were so much younger then but, as you say, wrist and ankle seals work well now, so they should make a big difference. I hope you try the diveskin with seals. I'll be interested in your findings as I'd prefer not to have to lube up.