I have that Wouxon KG-UV5D 2/6 meter handheld. I have tried various antennas and the best was a single band 6m telescopic. No surprise there. Alternatively, for dual band the Yaesu YHA-63 (supplied with the 817) was the next best and least likely to break. I also tried the Diamond antenna options and they were not even close. I use the Yaesu mostly and the telescopic when stationary.
Every so often at a local hamfest I will have my Wouxon and another guy has that Cherokee AH50, which is a dedicated 6 meter handheld. We give one of the local repeaters a blast and get some questions from other amateurs looking at the new and old radios.
The two main problems were already pointed out, lack of repeaters and inefficient "handheld" antennas. I am fortunate in my location as there are two 6m repeaters that are around 3500' above the valley floor. Even then, with the Yaesu antenna it struggles. I have not tried the simplex range using two of these KG-UV5D radios and Yaesu antennas. I would not expect much.
* I did test using a counterpoise for six meters on the handheld, which is ridiculous, but testing is fun. It did help both TX/RX, but having around 5' of wire hanging is not practical.