First off, I have to say that I find it astonishing–not to mention refreshing–that you are actually asking for input on revisions to the software. AMAZING!
I would answer that question by offering my thoughts on multi-effects in general. My sense is that most players–myself included– look to pedal-based multi effects to give them a programmable, space-friendly, and easy-to-navigate-live solution to replace multiple stomp boxes on their pedal boards. The key is that it replace those boxes without sacrificing too much in the way of tone. Line 6 has been moderatly successful toward this end with their MM4 and DL4, but the sound quality was never really up to par. That said, they are so versatile that many players–including touring pros–are willing to make the tone sacrifice in exchange for the versatilily.
That said, I think the starting point for any of the classic effects–chorus, phaser, flanger, tremolo–needs to be the classic effects pedals. There's a reason those boxes have withstood the test of time, and continue to be modeled and copied and cloned.
So with respect to the question at hand, I would suggest going back to the classics as a starting point, i.e CE1, CE2, Small Clone for Chorus; Phase 90, small stone, mutron for phase, etc.
I suspect one of the previous posters got it right with the suggestion of some sort of low pass filter on the delayed signal, since this is what gives an analog chorus it's characteristic "warmth", similar to the effect a rolled-off high end has on analog delay. Also, the ability to adjust delay time seems critical to tweaking the chorus to match changes in speed and depth.
Thanks for asking!