Music Hall 2.2 Cartridge Upgrade?

Being new to vinyl I have been more than pleased with my recent purchase of both the Music Hall 2.2 and a Bellari phono preamp. My next step will be the Project Speed Box. My question is, the cartridge supplied with the Music Hall sounds pretty darn good, but would upgrading to a Grado Gold, etc. be a good investment? I want the most bang for the buck to maintain musicality and ease of listening.......oh yea, and spelling skillz as well. Peace!
I used to have a Project Perspective and a Grado Reference Platinum ($300). The sound was very warm, smooth and lush. However I prefer fast, clean, and quick transient type of sound. So I switched to Audio Technica AT150mlx. I am now using it with the Rega P5. I like the AT150mlx a lot. So it depends on the kinda of taste you have. J&R is selling the 150mlx for $349 (list is $799.) I bought it from J&R.
I owned a 2.2 for awhile. You may want to consider a few things I tried. Keep the cartridge and get a hyperelliptical styli. I bought the LP Gear Rx9HE, $64.95. That performed beyond it's price point. It was the biggest improvement, overall. A better platter mat helps. I had the oppurtunity to borrow a few, they were all an improvement. The table likes a lot of isolation, butcher block/mdf, the more the better.
Thanks guys! Looking forward to trying a few ideas and see where it goes.