Here are the plug is that Sonar PE comes with based on your research:
SONAR PE includes
1. Session Drummer (very good)
2. Dimension LE
3. Rapture LE
4. Zt3A
5. Drop Zone
6. Pentagon 1
7. PSYN
8. Roland Groove Synth
9. SF2
10. Cyclone
1. I have never used Session Drummer because I have Battery 2 and 3.
2. Dimension LE is nice, but you will want the full version Dimension Pro. I own it and it's great.
3. Rapture LE is nice, but you will want the full version of Rapture. I also own it.
4. z3ta! is the full version I believe. That's is a great plug in with great presets and other free sounds available online.
5. I don't have it, but it's a basic sampler. Live has Simpler which is about the same thing.
6. Pentagon I have, but I have never used it. It's nothing next to z3ta!. Both are actually made by RGC audio.
7. Psyn I have never used. I didn't like any of the sounds. It's sounds like a bad analog emulation to me. That's just my opinion. I've had Psyn since P5 Version 1, and I've never liked it.
8. Roland Groove Synth is a bunch of old Roland drum machine samples I believe. That is what it is. Just about every peice of software with drum samples has it's own collection of classic Roland drum sounds, so this really isn't a big deal at all.
9. SF2. I don't really know why this is inluded. If you wanted to open a SF2 file, why wouldn't you open it in Dimension Le or Pro? You would have a lot more control over it then. I have SF2, and once again, I have never used it and don't like it.
10. I thought that Cyclone would be like Battery. It has 16 pads. It can play loops or on shot samples. You can even control the start/stops of the loops you are playing. Seems like a nice plug, that is until you begin to use it and realize that it doesn't respond to velocity at all. I actually asked them (Cakewalk) to make it responsive to velocity two years ago, and it still doesn't. Makes no sense at all.
Basically, you can live without most of those plugs. If you like Dimension and Rapture, you will want the full versions anyway. I had a lite version of Dimension that came with P5 V2 before Dimension Pro was released, so I got a discount on the upgrade. If you do go with Sonar PE, you will get discounts on the upgrades as well. You will like z3ta!, and I think they give you the full version of that. Everything else, I don't know. I think you could live without all of that stuff.