Move to MC Cartridge- Shelter, Ortofon?

I've been running an Ortofon 2M Black up until now. However, I'm contemplating making the switch to MC to go with an Technics SP-10 project (see other post).

The likely candidate for the arm is an SME 312- (see other post- help needed). Although I'm not a 'high-ender', I am reasonably particular- champagne tastes on beer budget and all that.

While I'm having the SP-10 worked on, I figure that I should put some serious thought to a cartridge. The 2M Black is a wonderful cartridge, but I want to take the next step up. Ortofon is the obvious first choice as the 2M certainly impressed me. Keeping in mind the 'beer budget', I found a seller offering discounts on the discontinued Kontrapunkt 'H' and 'B' models. I am trying to work out the 'sonic' differences between the models.

I want a cartridge with excellent PRAT, one that can really get and boogie/rock when called upon. The heavy weight and high tracking force of these Ortofon models does concern me (esp coming back from the world of MMs) I am also considering a Shelter 501 Mk2.

The setup will be called upon to navigate my collection of rock/acoustic with but mainly 12" singles. The 12" singles are usually cut loud and can put any system through their paces! Big dynamics, big bottom end and plenty of high hat and (real) strings with often an small orchestra. I don't want a cartridge that goes Ppphhhsssttt instead of a realistic ting and shimmer when a high-hat is getting a good work out (that is- I don't want that high rising frequency response).

Any ideas, views, alternatives?