I've been all about on the fly tuning changes and modeling for decades. Of course nothing will ever be exactly same as the original instrument but for me that has never been the point since I am not a cover artist. Creativity and the ability to travel lighter with an increasing sound arsenal that is inspiring is far more important than imitation. No judgement on those looking to get things to sound the exact same way they did 50 years ago, I love those tones but personally I am also looking for new tones.
Since the mid 90's I've owned just about every type of Hex pickup (Roland GKs, RMC, Fishman, etc) and for the last two or three years I have been using a Cycfi Nu pickups. As far as my personal experience these are the best individual string pickups if you are looking for flat response, minimal noise and minimal bleed. Joel has also made the pickup designs open source (MIT license I believe so useable for modifying, building and selling without concern).
I've also owned many, many processors starting with Digitech 2112 & 2120, the Roland VG-8, VG-88 and for a long time the VG-99 which for a couple of years has been going into an Axe FX II XL+. As of a couple days ago I am using an Axe FX III (WOOHOO!
). I never tried the Antares although it certainly looks interesting and I might pick one up just to check it out.
So, all that said, I found this thread because I really want to replace the VG-99. It is a bit long in the tooth to say the least but it seems like nothing has really exceeded it's capabilities. Bottom line, I am definitely interested but for me something foot switchable is critical. I like making fine adjustments on the guitar with the usual volume, tone and pickup selector knobs but I use too many combinations to remember them during a show.
As for technical issues, the biggest problem that I have noticed with emulation is noise while the biggest problem with retuning is string bleed. Latency isn't a problem with the VG-99 (although it is with the Axe FX pitch effect). The noise problems vary depending on the pickup type. There is the over sensitivity issue with unwanted finger, pick and hand noise particularly effecting Piezo pickups. Interference, crackling and hum from electronics is an issue with all pickups. There is also a problem with noise as a by-product of emulation, which in my experience seems to be more prominent as an additive effect of processing multiple pickups. Basically that is to say that a minimal noise floor is essential as you are getting six times the noise.
For the most part I have personally overcome most of the issues with noise and latency at this point, leaving the issue of bleed when it comes to retuning. If excessive bleed can cause weird glitches with electronic retuning but the main problem is the unwanted dissonance or doubling effect of a string crossing into the retuning of another. For me the Cycfi pickups have eliminated all of the glitches and I only find occasional issue with hearing a cross over when using higher gain. Hopefully this gives you some insight into the many issues. I think you will find similar comments experiences on the vguitarforums site and those guys would definitely be your target market for any hex pickup.
One last thing, I was going to add the links to Joel De Guzman's 4 blog posts on the subject of Virtual pickups, except I can't do to the forum rules. You can find them on the Cycfi site if you search for them by name "Virtual Pickup Placement" (parts 1, 2, 3, and Revisited). Funny was that I found that he just came out with a followup today after three years on software for pickup emulation that he has been working on which is titled "In the Meantime". As an aside, having worked with on my personal project I can tell you he is very open to collaboration. Something to consider. Cheers and best of luck.