I just put a pair of Genelex Golden Lion KT77's in my VAC Avatar integrated. It's been less that 20 hours but my initial impression is very positive. I agree with what Kiteflier said, better extension on both ends.
They may have better clarity than the SED el34's I have been using for the past year. The "may" stems from the fact that they sound more linear, offering a different perspective with less mid lushness, resulting in better clarity IMO, and for my purpose, this is good. If you are seeking more of a mid focus, the SED works well.
Please take into consideration that they are new and I haven't really had time to sit and listen much. I will follow up in a few days but thought I'd chime in with initial thoughts.