There are a few models of the IIC+, and within those there are variations. Additionally, many IIC were converted to IIC+/++ (some switchable some not). Some of the units are heads. Some are combos. Some were combos and turned into heads. Hell, some IIB's even had a type of conversion done where a IIB was made into a IIC+ by having a IIC/+ board installed to replace the IIB board.
There are two main preamp boards as well.
Which one of the amps is the new IIC+ to resemble? I was told it was cloned from the "specimen" in the Mesa factory. If you have an OG and you like it, you may not like the new one OR you may not like a different OG model compared to what you're used to.
There's so many variables that it's easy to see why there's confusion and why the new one will be different! If you have never played an original, at volume, side by side with one of the "modes" of a new amp, then you'll never truly understand the difference. You can't go by a youtube clip. You can't go off of the album which often has multiple layers/tracks/eqs/compression/etc. You need to be in front of one of these, at volume and there's a feel thing that isn't replicated in a mode of a modern amp, or in a digital simulation. You can get a lot of the tone, but the special sauce isn't included.
Back to the topic of the reissue vs the OG, I've seen a few pics of the innards of the IIC+ reissue. It's definitely a modern take on the original circuit. Look at the specs and you can see the weight is different as well. Since the components are different, it's going to be different. There's no way around that. Plus the old ones are 40 years old! Aside from caps, most of those components will be the same as they were back then. Will that change the sound? Who knows? Maybe the sound will be there but the feel won't be.
I preordered one when I heard they were limited production but then I've been told by 2 dealers and Mesa that there's no intention of stopping production.
I'm not sure where I will stand on it/if I'll like it until I try it.