Under gravel Filter for a planted tank?

I wouldn't use a UGF on a planted tank - a planted tank tends not to get the same vacuuming so a lot of gunk ends up just rotting under the filter plates, plus roots will cling to the filter and make any replanting a pain. Your canister alone would do the job. I find sponge filters pretty handy for calmer tanks - they cause a calmer flow and come out easily for cleaning, and work great. The powerhead would really be unnecessary.