In my Stiletto Deuce, I replaced the factory tubes with high-gain JJ ECC83's (12AX7) in V1-V2-V3, an standard ECC83 in V4 and a balanced ECC83 for the phase inverter in V5. After making the switch, IMHO the amp has about 10-15% more gain and attack.
With the amp in 50w mode and a clean boost pedal in front of the amp (I presently alternate between a Homebrew Electronics Power Screamer & Big "D" -- gain knob at 7:00, level around 2:00) in front of the amp, my Stiletto nails the EVH brown sound! Screaming natural harmonics, punch and crunch...pinch harmonics just jump out of the amp!
Initially, I was very disapointed with the Stiletto but after making the tube switch, I'm hooked. Blows away my old jumped JMP!
I also replaced the EL34's with four JJ E34L power amp tubes. Where I've read that some users say this switch makes the amp sound like it has a blanket thrown over it, I feel the E34L adds bottom-end and chunk sorely missing from the stock tubes. As I went back and forth between the stock EL34 & E34L, I noticed the stock EL34's sounded incredibly weak and thin in comparison. The EL34's stay put in the power section now.
Though I'm still using the 5U4GB recto tubes, I will be making the switch to GZ34's. I presently have the GZ34's in my recto and tightens up the amp unbelievably!