A follow-up…
Before my father died, I was visiting my parents' every other week when I wasn't working. There is a CycleGear store about 35 minutes from them, so followed boggy's advice, after a fashion. That store doesn't stock the suit, but CycleGear ships free over $99, and they accept returns at any store. Soooo... I ended up ordering three suits (!): M, L, XL.
Let me start by saying that I don't see how on earth FirstGear has the expectation that this suit will be worn over an armored riding jacket. Even the XL was difficult to put on, and way too tight and uncomfortable to wear, over my Tourmaster coat. Maybe if I wore a light-weight, tight-fitting leather jacket or Joe Rocket mesh sport jacket, but not mine. And their guy recommended I get a Medium! So that's FirstGear's fitting paradigm out the window, at least for me. I want to keep my hi-vz layer on top, anyway.
So, I ended up keeping the large, and returning, in person, the medium and the XL. In my fitting tests, what I found seems to work the best for me is, I can wear a thin long-sleeve shirt, followed by a thin LL Bean down layer I have (they call it a "down sweater" - it's very thin and light, but warmmmmmm), the FirstGear suit, and finally my jacket, provided I have the zip-out "insulating" liner removed. I wore this kit on my first ride of the season (about 1/2 hour) and it was 29℉ when I got home - I was still plenty warm. It was chilly inside my helmet, since I had to keep fresh air flowing to keep my visor from fogging.
Yesterday, I rode to and from work - the morning ride was cool and wet (not raining, but wet roads from rain the night before), but I was fine, and again when I rode home on drier roads. When I got home, it was 40℉, but I felt like I could have ridden comfortably all day.
For me, the sleeves are basically long enough, to wear under a jacket, that is; the legs are just a bit too long for walking, which for most people is perfect for riding, I guess, but I seem to have problems with legs hiking up higher than most in the riding position (knee armor in riding jeans always ends up too high for me). The leg closures have a grippy rubber strip inside to help hold them around your ankles, which is fine, but my riding boots only come up just above my ankles, so the legs tend to pull up off the tops of my boots - as a result, there's a cold spot just above my ankles, which would also end up wet if it were raining. Taller boots would alleviate this problem, but I've never found a tall pair that were comfortable. It's not a problem for my daily commute, but I'm thinking I might try to fashion some straps (stirrups?) which loop under my boots to hold the trouser cuffs down.
The suit is pretty easy to get into; the leg zippers open all the way up the the thighs. I've not needed to open them higher than my knees, and my boots drop right through. The zippers are covered with doubled flaps held closed with velcro; these flaps can be a bit of a pain to get properly folded up and sealed, but no big deal.
The collar has a soft lining and closes with velcro; they seem to have gotten the fit right as I find it comfortable and easy to adjust - takes the crummy Tourmaster collar fit right out of the picture.
All in all, so far, I'm quite satisfied!