I caved and bought this pack yesterday. I already owned several OH sets including the California Duo, Deluxe Reverb, Super Reverb, and Marshall EV-L. There's some overlap, but I actually like the Core Tone quite a bit.
I now have several V30 cabs and the Recto OS in the CT bundle seems the most balanced to me. The free Mesa slant cab is much brighter without as much low end and the standard Mesa in the Cali Duo bundle is a little darker and smoother.
Initially I thought the Cali Duo bundle would cover the 2x12 stuff for Voxes and what not but I never end up liking the results. I've preferred the Deluxe Reverb V30 for just about every class A type sound, it's just fantastic. The Mesa 2x12 seems too dark/smooth and the low end is kind of chopped off. The Vox 2x12 with the Blue speaker has a much fuller deeper low end while still being fairly smooth. I actually got a great result running a stereo cab of the Vox 2x12 Blue along with the Deluxe V30.
The Deluxe Fane is interesting compared to the other two previous speakers. The Deluxe C12R has that scooped Fender sound while the V30 is fuller sounding with that little punchy high midrange which is the signature for that speaker. The Fane seems a little darker than either of them but still again full sounding and not muffled. I think it's absolutely perfect for the Tweed Deluxe sounds.
I didn't spend as much time with the Marshall. I had been planning to buy the checker 4x12 H30/M25 set (and still probably will). Compared to the new stock 57 (4x12 with 55Hz M25 I think), the Core didn't have that same smooth/pushed sound, it seemed a little brighter overall. I think it may have been a touch brighter or more scooped than the Mesa cab with Cali Duo set.
Overall, it's a fantastic set and if I started with this one I probably would be very happy. I don't think I'll ever use any of the Cali Duo cabs anymore to be honest.
My favorite IR's overall:
1. Deluxe Reverb V30 - perfect for all Class A amps
2. Mesa OS V30 - perfect for high gain
3. Marshall 4x12 55Hz M25 (factory 57) - perfect for bright vintage Marshalls
After those, the other two Deluxe speakers (C12R and Fane), Vox 2x12 Blue, and Super Reverb 10" are great options.
Side note, any chance of a stripped down bass cab IR?