I guess you bumped it for more opinions? Here is my two cents. You can keep thriving plants with an UGF. As others mentioned, in some cases roots might get tangled in the filter, which can be a pain. This does not always happen. I have kept Swords, Aponogetons, Crypts, Vals and other plants that can create a lot of roots in a tank with an UGF and never ever saw this happen. YMMV. I see good growth in root feeders in that tank. Many plants feed from the water column, and do will care a whit if you and an UGF. Those that are root feeders need a good substrate, but an UGF has no relation to that.
If you are setting up a new tank, there is no point in wasting money on an UGF. The filtration that it offers can be accomplished with better filters, and you will have less worries. If you have an established tank that you want to keep plants in and it would be a serious pain to remove the UGF leave it be and don't worry about it. If you have a powerhead then you can set up a Reverse Flow UGF as was described in posts above, which is a nice approach.
Other factors like CO2, proper ferts, a good substrate (if you are keeping root feeders), and adequate light levels are vastly more important on successfully keeping plants than whether you have an UGF.