As a long-time BT player, I have not found them over-powered in general. I am on record as saying they are IMO one of the most balanced lists going. I might add that I also think they are one of the most flexible, having the potential to play many strategies.
That said, the BT have to set up their army to play the given strategy, and can be very brittle if that strategy is countered. One of the main ways to counter them is to place BMs on as many un-activated formations as possible. The point is they are intended to hit hard but also to be brittle. If Eldar are allowed to hit, they will hurt; if you can hit them first, they are more likely to 'fold'.
Back to the thread, on the Void Spinner I agree with others that it should not be any cheaper, though I am not entirely convinced on the E-UK price increase either
I would be interested to hear any feedback on the other EoV, especially the Scorpion which seems to have gone very quiet.
Ditto the HB changes and what impact they have had (if any).
And to the recent comments, I have always felt the SoV formation is a mistake. That said, and given the NetEA direction here (and on the FirePrism) the FP does seem to be balanced against the Falcon at roughly 50 points. each.