Welp...I was wanting the CA-2A and see that there's a weekly special I got via my email, that includes both for $75.  That's $24 cheaper than just buying the CA-2A.  I've got SO MUCH to learn at this point, not sure if I really should be stacking up on more PC modules, but the CA-2A can be used as a VST, as I understand...not that that really matters I guess in Sonar, except I could put in on the busses then, I guess....if one wanted to.
 
From reading, it appears the PC4k is capable of slamming, like the PC76, but is more neutral sounding.  Better for vocals maybe.

Am I on the right track and is this a good deal?  ...realizing that's subjective.  Seems there was a deal in the past that included ALL the items...concrete limiter, PC4K gate, etc... but forgot what that price was. 
 
and while we're talking comps... what do you all think about the PC4k buss compressor?   Seems nice to me...but like I said, so much new to grasp, I'm probably a definition of operator error with it at this point. 

The PC4K is a model of the built-in compressor in an SSL mixer. It is pretty good and very simple to use. The side chain is a great feature. Don't expect it to do limiting very well because it is not designed even in the mixers for that purpose. I use it quite a bit on all sorts of instruments besides vox tracks that need just a tad of help. It is well worth the investment in this bundle. With the CA2a, the 76, and the 4K I have been able to relegate all my compression needs in the box now. Very handy!
If you get a chance and don't have it, the Concrete Limiter is a must have. It is a great improvement over Boost 11.

edit:
I've found the link to the shop, but cannot post it here.
 

+1 for the Concrete Limiter as well.
Probably one of the best plugins offered by Cake so far and has finally replace our old standby, the L1

The Concrete Limiter is fantastic on individual instruments. I use it all the time on drums to tame peaks and bring up room ambience. It's also a solution for vocals with widely varying levels. I don't use it on program material, though; I'm a fan of the Waves multiband limiters, however with moderate limiting the Sonitus Multiband set for the limiting option works surprisingly well. It also offers the advantage of letting you "get inside" the limiter, whereas the Waves maximizers basically just give you a couple controls for the overall characteristics.
 

Craig is absolutely right about the Sonitus Multiband. It has saved my %&^$ more than once! And it was a great learning tool for me to learn how to use the multiband in Ozone as well.

At first I found it hard to get the sound I wanted from the 4K Channel Compressor, so didn't use it as much as the others.

Now I like it a lot, and use it on a variety of sources. It is definitely worth having.

I also love the Concrete Limiter. I recently opened a project that I had started when I first got the CL, and was amused to find that I'd used it on every track... I am a little more sparing with it now. :-). I do like using it on drums, and on the master bus.

Back to the OP. IMHO the 4K is great.

I've never liked it. I guess my levels are to low or whatever, but I can't hardly get the meter to light up at all. I rarely like to hit -3db in gain reduction anyway. I'm not a big fan of the gate either...All other Pro channel plugs I love and use often. The concrete limiter is a very handy tool and I love the bus comp.

I found that I had to ignore the meter and listen instead. I also like the gate as well. The side chain is really handy.