I've got:
* Blue in my 6V6 Deluxe (home practice amp)
* Gold in 6L6 my Deluxe Relic (rehearsal amp)
* Golds in my 2x12 (gigging rig with Doppelganger)
The Golds are designed to be a 50w Blue, and they are very similar. The only difference I find is that they need more volume than a Blue to work best and get the cone moving. But you'd expect that, being a higher rated speaker, that the sweet spot is that bit louder......