Hi all,
I’m In the market for a speedsuit (probably taking the Velotec Dynamic or Pro Aero suit).
Will use it mainly for the occasional speed fest and crit races/rolling gran fondos.
A few things I’m trying to wrap my head around:
Cheers
I could be wrong but I think I’ve seen on some TT start sheets the requirement for long sleeve skinsuits. I’ve no idea if black will absorb the heat more or cool down faster but I’d avoid personally wearing something black with the muppets on our road (the kermit type is probably more observant 
).
Not an expert, but i believe unless you have perfectly fit sleeves with no wrinkles, the long sleeve has a good chance of being slower
You could also look at ‘aero sleeves’ like those from Nopinz or Rule28. Might be decent enough to just go short sleeve and wear the aero sleeves when desired.
If I recall (it’s been a while) shaving the arms of a rather hairy individual can save time on a TT, based on the Specialized Wind Tunnel tests. I forgot how much it was. Legs were up to 40s, even braiding long hair can save 14 seconds. I believe the arms on someone particular hairy was up to 12s. So It’s possible you would save time so long as the sleeves are well-fitted. How much time you’d save would depend on how fast you go: the wind tunnel tests were at 40kph. So the slower you go, the less of an effect it’ll have.
That being said, even the best materials can get warm, and skinsuits are not typically made from the most breathable fabrics. So if you’re not into heat, I’d pass. My newest skinsuit from Pactimo is great, but I honestly don’t like the sleeve length, which is supposedly “short sleeve” but almost comes to the elbow. In my opinion, if it comes below triceps, it’s no longer a short sleeve.
As for requirements: USAC allows sleeveless jerseys/skinsuits in Time Trials (current rules, section 1J5-a), with no mention of sleeve length beyond that. USAT doesn’t have rules on the sleeves, only the materials (4.7a and 4.11cii).
Regarding color: my newest skinsuit isn’t black, but it is a charcoal greyish mix. I don’t find it any warmer than my previous skinsuit (blue), though it’s a much better and more breathable material. Though the color can make a difference, I think the material will have a much greater effect. But I have no way to confirm that. 
I made the decision to just buy a short sleeve suit, and the Rule 28 aero sleeves fit nicely around the elbow - almost no creases. They did recently post something on Instagram stories…
Subject to my memory… aero sleeves are a fraction slower than non-Tarzan arms, but textured/smooth sleeves interact differently with base layers and can be faster than skin in some combinations. The long sleeve suits are always faster though IIRC (assuming good fit).