I think the original post was "how is the Pro-Channel"? It didn't specify a specific module so in that regard I'd say: It's amazing. You can create complex channel strips and save them as presets and also include 3rd party plugins in it. What's not to like?
 
As for individual modules, hopefully you go the CA-2A when it was recently offered for free. It's bloody amazing. I ponied up for the Concrete Limiter and pretty much use it for all my limiting/mastering needs save for complex mastering projects. The Softtube Saturation Knob is another go-to for me. EQ: works great for me. With the architecture of the pro-channel I can create a fantastic chain with EQ pre and post compression, and make simple control knobs for the whole chain so it's easy to dial in a sound using six or more processors with just a few knobs. It's one of SONAR's greatest features. If they eventually add a robust delay I will hardly use the fx bin anymore. :-)
 
 

"How good is the pro channel? Can it replace something like the SSL plugin series by waves, or would you still be better off using that?"
 
to be honest, whole Pro Channel is just a useless eyecandy, and I can tell you why - it's not possible to import/export/copy/paste prochannel across tracks or projects, so let's say you create a perfect EQ on one track, good luck manually adjusting rest of the album because it's not possible to just copy it (unlike FX VSTs which you can just drag and drop across projects freely!)
another problem is the modules get toggled randomly by themselves, happened to me plenty times, random modules on random tracks, definitely not a "user error" although at first I thought I could have just pressed something wrong
 
EDIT: according to this documentation it appears to be possible to save entire prochannel stuff, but no sign of individual module settings saving
 
 

tzzsmk
"How good is the pro channel? Can it replace something like the SSL plugin series by waves, or would you still be better off using that?"
 
to be honest, whole Pro Channel is just a useless eyecandy, and I can tell you why - it's not possible to import/export/copy/paste prochannel across tracks or projects, so let's say you create a perfect EQ on one track, good luck manually adjusting rest of the album because it's not possible to just copy it (unlike FX VSTs which you can just drag and drop across projects freely!)
another problem is the modules get toggled randomly by themselves, happened to me plenty times, random modules on random tracks, definitely not a "user error" although at first I thought I could have just pressed something wrong
 
EDIT: according to this documentation it appears to be possible to save entire prochannel stuff, but no sign of individual module settings saving
 
 

feature request?

Personally I think the Pro Channel is the neatest thing since plugins. Low CPU use. Powerful modules with easy to use GUIs. And fully customizable. Plus you still have the FX bin. I was for it from the start but I saw it as a sleeper that over time would gain a huge following. Those that adopted to it were rewarded with outstanding modules. However those that ignored it failed to see just how good it is.   
 
It does what CW said it would do. Its sort of the secret weapon we Sonar users have. 

"feature request?" not really because I think the whole concept is wrong as it is now...
as John mentions pro channel potential, I really liked it in the beginning too, it does basic things without need for additional plugins, but once you start treating things seriously, having multiple projects, lots of tracks etc.. the prochannel weaknesses pop out really harshly,
and for ex. there is no multiband compressor, volume/gain rider, gate+comp, metering/measuring tools and so on,
potential of pro channel is to be wasted as it's CW own "platform", so not many third-party devs will make modules for it, which as a result leaves sonar users choice of either using pro channel or VSTs, and usually people choose the more convenient way

I love the Pro Channel and use it for almost everything. I do still resort to separate FX plugins for certain things (delay for sure, and a few other special plugs). Overall the PC is very good although, I do wish you could save presets for the individual FX in it. Yeah, I know you can save chains and stuff but, that's less convenient IMHO. I would still love to see more 3rd party Pro Channel FX from some of the big guns!

Everyone in the DAW world of recording makes the same mistake of forgetting how many classic alltime live-forever recordings were made on overworked beatup running on a prayer gear! The endless choices that we have in plugins really stymies the creative ends. We all spend hours sweating bullets over which compressor, gate, EQ, etc.... to use. I think we all forget that when you walked into a certain studio in the OLD days, they had one console and you were lucky to have a few choices of outboard compressors and really lucky to have a gate. Heck, some of this stuff wasn't even invented yet.
When we bought FX pedals back in 19 hundred and LOL! we weren't interested in what the pedal was designed to do. We were interested in what we could MAKE it do!
My point is some of the best music in the history of recording was made in a very limited box of tools. While it is nice to have 27 Eqs to choose from, you really only need 1 or 2. The end result which is the song will come together much quicker and much more enjoyable by just using a few but carefully picked plugs. Whether it's Prochannel, which I do love, or something else.
If the song is good the tools won't matter!!!!

Sidroe you're totally right, but I'd say this doesn't have much to do with the original question of the thread creator ;)

I think many PC units are quite good. I don't personally like the 1176 but CA2A is great, the QC would be suitable for 90 percent of my EQ needs if I didn't own/prefer ProQ2, Concrete Limiter is good and straight forward and the SSL bus thing is good. The main thing I really don't like about PC is the interface jumble it creates. But I'm in the minority there. It'd be better if I could retain gain/send/pan/level controls in the inspector with PC open but I also understand why I can't.

Sander if you have a dual monitor you can have the prochannel open in the CV and the Inspector view in TV.