Bickford, I think your Endura is a good starting point to answer your questions. If you want something close to the same size as your Endura, then get the standard Griptilian. If you want something smaller, then the the Mini-Grip is the way to go. If you're happy with how your Endura does with edge holding then the 154CM blade Griptilians will offer similar performance. If you want crazy edge holding capability, at the expense of reduced corrosion resistance, get the D2 blade. I have the old 440C black blade full size Griptilian, and it's been a beast of a knife.
The only thing that I can say negative about the Griptilian is that the wide rounded grip doesn't carry as easily in small or tight pockets as thinner knives like the Endura. Conversely, that wide rounded grip makes working for extended periods far easier on the hand than using something with a thin, flat grip.
I think the Griptilians are really hard to go wrong with. If, however, you want something different - thinner, smaller, bigger, whatever - tell us what you want, and we'll throw more suggestions out.