Thanks, communist!
Change tempi more often even if Brahms did not indicate to.
I used to have more tempo changes before my teacher convinced me that this "quasi-Chaconne" should be played throughout in relatively steady pulse (especially theme + first 3 variations, because there is a continuous composed speed-up effect anyway, 1/8->16ths->16th ternary->1/32s). Having said, I still agree with you that it's interesting to explore how it feels with more volatile tempo, or maybe just a bit more rubato at the right places.
Use more pedal, with too little it ruins the orchestral effect.
Maybe you would have liked my original idea of the piece better, because I used to apply more pedal, especially in Var. 1, but then the LH pauses get completely lost, and now I like the more rhythmic feel that is obtained with less pedal.
More dynamics, in Brahms you rarely see FF or PP, so make the Ps and the Fs more varied.
Good comment, I fully agree. Thanks again!