My short answer having owned both the 26 and the 6 is yes to both questions Balanced sounds a bit better to me than single ended but that could have been the difference between cables but the 26 is a bit more open and transparent and the lowest notes hit with more authority, mostly likely due to the stiffer power supply. I have also found that the greatest benefit of balanced connections is in an electronically noisy environment and the entire audio chain is balanced - source to pre and pre to amplification.
Having said all that, the BP6 is no slouch and if you can't directly a/b the two together you would never know what you may be missing. If you have invested in single ended cables and like them, and the connectivity options of the 6 work with your system, the simplicity of the 6 really appeals and the savings can be put towards the Bryston amp that is in you future.

If you would be bothered thinking you are missing the last bit of detail/transparency/noise floor/bass slam, then go with the 26 comforted in the fact it doesn't get much better than that.