There are 2 sounds to be concerned with, the sound you hear to inspire you and the sound out front.
The 2 are not always the same. The sound engineer will always control your FOH sound, even if you blast from the backline and its their role to balance it with other instruments, especially when there are 2 guitarists. This is actually my main concern and the one I have least control of. The best way to get a bad sound from the engineer is to tell them what you think...let them get on with it.
If your base sound is good as per the start of this post, they will have to work hard to screw it up. I don;t change much eq wise at all, no tone shaping..
I try to keep mine simple and listen if they have any comments but to date, since I've gone direct, no engineer has ever asked me to adjust my e.q. or commented that there is any issue...