The people that I have seen successfully using UGFs and RUGFs are the people who have been using them since they were 'in' or the best method at the time. I am guessing you got used to working with them and know exactly what it takes to prevent problems.
In my opinion a big difference is that when HOBs, canisters, and UGF/RUGFs are neglected it is easier to fix the problem with HOBs and canisters. You break them down, clean them, and get them running again an hour later. However, on UGFs and RUGFs it is more work to fix the problem and riskier for the tank. You inevitably stir up all sorts of debris back into the water column (looks and smells like sewage).
I don't think any are more maintenance than others. You either do a lot of vacuuming with UGFs, or cleaning filters with HOBs and canisters. The tank doesn't produce any more debris based on filtration, so the same amount of debris needs to be removed from any one of the filters.
I like sand a lot better. I have heard some horror stories about DSBs, this is partly why I didn't use one in my reef. The sand I use in all my tanks is Estes' Ultra Reef. It is not a true marine sand so it doesn't alter any chemistry. The most important thing about this sand in my opinion is that it is extremely uniform in size, and the size is just large enough to not prevent oxygen from getting to the entire sandbed (even in 2" of sand or more). I always recommend against cheapo sands because I think those sands, even the better ones, can contribute to significant problems eventually. These problems are the issues that are brought up against sand in any discussion of sand vs. gravel.
With sand effectively all of the debris stays on top and either keeps moving with current until filters grab it or collecting in a couple small piles that are easily vacuumed during a water change. Some very fine debris will eventually collect in the sandbed, but not nearly the amount as in gravel and not enough to turn the sandbed into a nitrate factory.
With sand in my tanks there is enough flow to keep debris moving until my filters grab it. So during a water change I have a net over the gravel vacuum just to keep fish out, I start the siphon, go do something else (computer, TV, dinner, etc.), come back, start filling, go do something else, and then done. No need for vacuuming.
For people not used to dealing with UGFs I think it is much safer for them to just go with a HOB or canister.