1. slow ui? Yes, comparing with r6. Especially with big flacks and dsd.Some concerns around slow UI and not accessing Play store very easily, or possibly the iBasso being not very good Spotify? Also the R6 is top of Hiby's range but DX150 is the lower sibling of DX200.
Will the iBasso or Hiby R6 be better?
2. With Lurker-s firmware you get google play services and play market out of the box
3. I’ve owned dx200 and dx150.
I can’t hear dx200 with amp1. Only amp8 helped me(it). I don’t think that dx200 has better sound quality. The are different from each other. Depends on your own preferences. Some people preferred dx150 over dx200 with stock amps.
4. R6 is not the top from hiby now. R6 pro is.