Lighter gauge flatwounds for a 5?

[Calaverasgrande]

Hi gang, I have had the same strings on my Musicman fretless 5-er for almost 4 years now. I think it is about time to move over to a new set. I am kind of bored/annoyed with the tone since I started using a flatter setting on my amp. I feel that flatwounds may sound better. However it came from the store with a very light set of roundwounds. I have gotten used to these strings and now tune to C instead of B on this bass.
Now I have been looking around for some similar gauge flats but they all seem to be even heavier than comparable roundwounds. Anyone else here playing a five not tuned to B or E?
Been thinking about trying Ernie Balls or DR's. Not so sure abot other brands.

[Calaverasgrande]

Oh and I realize that some folks will just say "whatever sounds good to you" etc. Well I dont really have the time and money to try 10 different brands and configurations of strings. Not to mention re-doing my setup for the tension and gauge of each set!

[Mastermold]

Well I'm using TI flats in standard tuning and they're light, and the tone is fat and warm.

[DavePlaysBass]

TI flats or light gauge Sadowsky Flats come to mind. The TIs will be lighter.