Should I convert this Bridgestone MB3 to SS?
or leave as is....
It's all about personal preference. Would you like it or ride it more as SS?
I would first modify it to accept a different color of water bottle cage.
How come you want to? For fun?
SS mountain bikes do seem like a lot of simple fun. Would convert one myself if a junked frame ever turns up.
If you want to ride long distances and carry a bunch of stuff around in your panniers, no.
If you want to play around town or ride some mild off-road, yes definitely.
If that were my bike, it would be SS. ...and the pink cages would be gone :-)