Surprisingly this reply has got Ginson content. Wait and see!
I read a lot of positive things about flats here and at the ole Pit. I serieously tried them. I put a set of d'Addario Chromes on my Bicentennial and the sound just died. Basvarkern heard it. I also used them on a CIJ P and it was alright, but not that good.
A year ago I bought a limited edition Burns Shadows Bass, which has a Chinese routed body, but it's assembled in the UK with UK parts. A great bass. It comes standard with Chromes and it's a nice bass with them. I called the owner of Burns UK who's a luthier himself: Barry Gibson
He told me the thought the Shadows Bass sounds best with Chromes so I kept it that way. But I didn't use it often...
A couple of weeks ago I mounted some normal d'Addario rounds... And gee! The bass came to life! It was not more than a nice sounding bass, but now it has thunderous lows, zingy highs, enough midrange, and the sound reacts more on the different pick up configurations. Last couple of weeks I only play that bass!! I mailed mr. Gibson and he was happy to hear about this nice result.
So no flats for me again!