mm or mc cart

I have an entry level MM rega cart for my rega p9 TT. Is a change to a MC cart a big step up in sound?
I think, this will depend on your Phonosection, but normally: YES
Better headroom, better detail, improved speed and timing, but when the Phono Section is not that great, try a High Output MC. Makes Life easier.
To find out for yourself, I'd recommend trying a Denon DL-103 (available for under $200) to see how an MC sounds in your system. You'll need a phonostage or step-up transformer capable of handling a low-output cartridge. God luck, Dave
either way, an upgrade will enchance your table, which is a classic. what phono pre are you using?
Try the Exact2 Rega MM cartridge. I just got one for my P5 and it is a tremendous performer PLUS with Rega cartridge on a Rega TT you won't need to add spaers to you tonearm to get corret VTA.