Just picked up three new cartridges to play on a KD 500 with Grace 707 with a Shure M75ED.

Empire 999 VE/X, Ortofon FF15XE, and an AT LS 400. My questions are any of these compatible with my tonearm regarding compliance?.Also will any have the potential to be better than the Shure? It is a PITA to mount and align catridges in the 707. I also have a Pioneer PL12D which I could play with. Thanks in advance.
Compliance is another one of those things that seems like it should be a big deal until you actually test it out and discover its not all that important after all. Which if you go on the Origin Live website and read up on their tone arm design philosophy you will find that is pretty much their view too. 

So to answer your first question yes they are all compatible.

Also will any have the potential to be better than the Shure? Sure.

Sorry to hear your arm is such a pain. Might be something there to consider for next time. Oh well look on the bright side. By the time you've swapped em out four times you'll be so good it won't be a PITA any more.
As far as compliance goes I have to agree with Miller here.

There are combinations on paper that should never stand a chance of working and yet sometimes they just do!

My opinion even though it may be a pita to swap carts around there is only one sure way to know......

I have run some supposedly unholy combinations that worked out ok, maybe not something I would recommend say but not the "resonance all the way to Mexico" as was suggested it would be!

Out of those 3 the Empire just may put a grin on your face imho.
Thanks for all your replies. I'm still learning. But I feel confident coming here with what might be considered inane questions and get reasoned answers. "Shure. Sure" cracked me up. I paid $100 for this tonearm BITD. I can't believe how expensive they have become.  I picked up the TT for a song w/o the Infinity Black Widow tonearm 'cause the TT was scrapped to sell the arm separately. Crazy.
Not so crazy, or at least not uncommon.

I sold my Denon 1250 cw infinity black widow to Someone who had been begging me to sell them just the tone arm and I refused.

In the end they bought it all just for the Widow.

So that tt might also have been junked or sold cheap minus its Widow.
Also will any have the potential to be better than the Shure?

Surely it’s Grace F9, F14, LEVEL II
with huge potential over your Shure cartridge.

Also a Grace cartridge must be on Grace tonearm (you already have Grace arm) if you want the best synergy expected by the manufacturer. I don’t use Grace tonearms, but i use Grace cartridges.

The best Grace are high compliance cartridges, but it depends on the styli (not all of them are high compliabce). I would look at least for F9 line with styli like F-9U (Utility 4 LineContact type stylus) or F-9F (Discrete 4 Shibata type stylus) if you want maximum frequency extention on both ends, minimum record wear and long life-span. Those two are better than classic F-9E (Elliptical) which is very popular too.  

RS14 styli are latest design from the 80’s, they are better than RS9 and fully compatible with F9 body. Normally they are expensive, the most expensive are F14BR/MR (Boron / MicroRidge) or F14R (Ruby). There are also Sapphire cantilever models, but almost impossible to find. Their RS14L (Luminal Trace) is reasonable prices and very good if the budged is tight.

Grace LEVEL II is my favorite series of cartridges from this manufacturer. Extremely rare, sound quality is mind blowing!
Hi analogvm15,

all three of them will be fine mechanically suited to 707.
Sonically the Shure will be bright, the Orofon inoffensive and the Empire a better match (consider that 707 is a lively arm).
Thanks everyone again. Shure gives me some things to ponder.

Shurely you jest.......