What kind of duty use are you anticipating? That's the most important question.
Personally I've tried out many knives incl. Spyderco's Delica, Endura, PM2, Police 3, Ulize, etc. I've got 6 years on the Jon and I've also carried ZT, Extrema Ratio, Benchmade, Pohl Force and many others.
Regarding the Delica, I found that a Leatherman Charge will handle everything a Delica will. If you're already carrying a multitool then I'd either upgrade to a Endura or something else in that size range. Mostly because of the ergonomics while wearing gloves and the added blade length.
That being said, the Delica is a perfectly capable knife. Solid lock, good steel and it's light and carries very well.
At the moment I'm carrying a Benchmade Contego. I've found it to be the best duty knife for my requirements. Its not perfect, but its the knife that's gotten closest.