I substituted a set of Ernie Ball flatwounds 40-95 with a set of Rotosound Billy Sheehan 43-110, remembering a good first impression.
Good news: I can stand my ground again against one of the loudest guitarists in the universe.
Bad news: I loved the tone of flatwouds and these steel ropes are making me upset and doubtful about my calluses.
I think that what made me disappear in the mix was the lack of attack of my old strings. Listening to recordings I cannot find defects in the tone.
Maybe it was a lack of attack, do you find a difference between flatwounds and roundwounds?
Maybe it was size: do yo think that larger strings have more bang?
Maybe it was fret buzz or that slight overdriven attack of roundwounds played with intensity.
I play a jazz bass style custom bass, with just a touch of bridge pickup and looking for a burpy full bodied sound.

I have thought that a larger gauge string has more punch, but I was comparing rounds, not flats. You would think that would be true with flats, but you may need to try another brand of strings. I haven't tried the EB's but there may be a brighter flat out there. Have you tried TI Jazz flats, D'Addario Half Rounds, GHS Brite flats?

I just installed a set of D'Addario Ground Flatwounds/halfrounds, or whatever they are called, on my 5 string. Definately brighter than Chromes or TIs. Easier on the fingers than rounds but not nice and smooth like flats. Personally, I don't like the tone, but I am not playing in a loud band. They may be a good compromise for you.
Rocky

I'm pretty sure the effect you've noticed is that the rounds have more overtones; these higher frequencies cut through the mix more. The flats have less overtones and more fundamental, so need to be louder since our ears are less sensitive to those lower frequencies. If you liked the tone of the flats and want to keep it, you may need to either get a bigger amp or get the guitar player to turn down (Ha! ROFL!). I've had great success when I've convinced the guitar player to turn his amp around so it faces him like a vocal monitor; but I've only been able to accomplish this in venues that have full P.A. support.

Also, Curious as to what kind of music are you playing.

This gig is a cover band, but I am studying jazz and would like a more original gig. Previously I was in a more classic rock gig, there was more space there.
This gig is like classical music: you have to play everything in as it is written every night.
This is the song list if you are curious:

1. you ougtha know
2. seasons change
3. sweet child o'mine
4. trashed
5. too long
6. I will survive
7. who knew
8. just let the sun
9. real gone
10. piece of my heart

11. crazy
12. one
13. nobody's wife
14. we are
15. don't bother
16. it's my life
17. creep
18. you shook me all night long
19. beat it
20. intellectualise my blackness

I think that roundwounds do "speak" more quickly than flats.
I agree they have more attack.

For that type of songs I'd go with the rounds you really need the highs in there.

Great set list, you have a bunch of great songs on the bass front.

Yes, some of the songs are an interesting playground, like Too Long. We have a singer that used to play bass :-)

Where did you find sheet music for "Creep"? I didn't think Radiohead used sheet music(it would surprize me if they could read it.)
Playing songs exactly the same way every time would get old pretty quick. Guess I'm just too 60's.
But then, I never saw much sense in being a two-ton portable juke box...