Sorry for the delay, been a very, very busy holiday season!
Tough questions to answer!! I play them both equally, although probably the C+ a bit more because it is newer.
Bottom line: they are both great amps, the jp2c is feature-rich which is awesome, the C+ has one usable channel in my opinion; you have to immediately cut the volume on the guitar, or, volume knob 1 or you will be blown out when switching from lead to clean.
The lead channel on the C+ is fantastic, but unforgiving. I've been a long time lurker on this board for years and a top complaint is that the amp "changes" each time you use it. I wouldn't go as far saying this is 100 percent true but the C+ does need a tweak or two every now and then, it isn't much but usually a slight adjustment with either the lead drive or the lead volume or mids (I keep my mid knob between 4-5, and dropped near the bottom on the slider) and sometimes the middle slider will need to be boosted a titch. Could be ear fatigue too, I'm far from an expert. In addition, the lead tone is much more defined, I feel, and you really need to master your chops or it will come out in playing.
The jp2c is consistent. Like a pair of comfortable blue jeans. It sounds phenomenal, but personally, sounds more like a tweaked Mark IV (which I've owned, not a modded Mark IV, but a Mark IV). But in honesty, the Mark series is an evolution of the "Mark sound" so this makes sense, and there is nothing wrong with that. All Mark series amps I have played are great and they all have inherent tonal characteristics of one another.
Barring a medical catastrophe I don't plan on selling either. I've been pining for a IIC+ for 15+ years! It's a phenomenal amp and if you can afford one, buy it! You won't be disappointed. But if you can't afford one the jp2c or Mark IV are solid choices.
Again, sorry for the delay, and feel free to ask questions!