Thinking about getting a full belt, as none of the cage designs really fit the bill, so to say. My question is why don't I see more people use the double rear cables instead of the single one? Seems like a better option for hygiene. What is the downside?
I can think of a few possible downsides for the double cable type... They might be less comfortable when sitting on them due to their position. They may be more difficult to adjust correctly, or at all, as where the single cable runs doesn't change shape as you walk, move and twist, but cables running over the muscles in your bottom can't be too tight as your legs move back and forth and your muscles contract and relax. They may also be more likely to show lines through clothing.
If you are looking at a Chinese belt get the one with the double cables. The way their made if you don’t like the double cable, you can change it to a single which is what I did with mine. I have no hygiene issues at all with a single.
Conversely I have two chains on my generic Chinese Y belt and they never caused a problem. The belt sits so they press into my buttocks (which tbh do carry more weight than they should) just enough that they aren't visible through jeans or flannel trousers with thicker underwear. Compare to my NeoSteel rear strap that I could never get the right 'horizontal bend' to such that it didn't dig in either while sitting or walking.
Good question. I haven't used a single/double rear cabled design before (only one with a wider continuous metal band). What I can say from my research is that it's a style that Neosteel (the belt I've used before) have used in the past (with two chains instead of cables) but has been abandoned with the newer designs (System, Masterpiece and Spaceless). Only the older "classic" belts are available with double chains. I would expect double chains/double cable to be cleaner for long term wear (specifically going to the toilet), whereas it can get a little tricky with a single cable. That being said I think it might be a change that was made for comfort and other practical reasons.
I would recommend steel rod (~4mm). Available in Neosteel and much hygienic than cable (steel is not porous as any plastic cable coatings are).