I'll throw in my recent experience as well for any prospective buyers. It would be so nice to have a place to try some of this stuff on back to back!
I was looking to try a onesie, having custom ordered a top shelf one before for motorcycling and hating/returning it. I was skeptical, to put it mildly, so I had very low confidence this would work out. I was pleasantly surprised! I went with a CKX Elevation Zero non-insulated because it seemed like reasonable quality and was on closeout. The fit isn't great, but it "fits." I'm 6'1", 215, 46" chest with long arms and ordered an XL. Torso length is pretty darn spot on, which was a nice surprise (doesn't ride up into a wedgie), and arm & leg lengths are good too. Overall, the fit is pretty baggy throughout, which I sort of expected in the torso so it wasn't restrictive, but the arms and legs are also baggy. The leg cuffs don't cinch at all (which I knew ahead of time from a review), which wouldn't be a big deal except they are pretty huge...feels like wearing those super wide leg jeans that were popular in the late 90s.
The material doesn't breathe real well, which is a primary concern for me because I sweat a lot, and the zippered vents are TINY and not very well placed. I can't even tell if they are open or closed while riding. Might make a good trail riding suit. It doesn't bunch up anywhere or get tight around knees/elbows, on me anyway, so that's good. The hood is removable, which is super nice. I've tried it both ways and would rather remove it and just carry a beanie unless the weather is real nasty.
I have a bone to pick with the leg zippers....who on God's green one thinks that anything other than full length zippers are acceptable on any bibs or monosuit??? It's asinine. Unless there is some requirement to have cargo pockets...and pockets on the front of the thigh would just be unacceptable, for whatever reason...there just isn't an excuse.
Overall though, I'm happy I tried it and I will be looking to upgrade maybe next season. In a world of $800-1200 monosuits, I'd say this one is definitely worth the ~$320 I paid for it. It's 100% livable on all but the warmest days and would make a workable backup or a great "entry level" suit for someone else to try if they are feeling out a mono. Having had a poor experience with monosuits in other applications, I'm happy I tried it and don't regret trying a cheaper one, knowing it probably wasn't going to be what I ended up with. Going to do my due diligence this time and try a Tobe on (for the reputation and the Sympatex), as well as a Klim. As long as the fit is as good or better than the CKX, it will be a no-brainer.