The presets are simply just the existing components being reconfigured and frankly, as I find with most presets, not very useful. To me I think to get good, useable sounds out of TH2 Producer (the one that came with Sonar) as it is is very possible. The full version is indeed awesome but IMO opinion it just gives you MORE... like lots more... but it kind of just builds on what you already have. Like with GR4 Sonar I found it unusable whereas GR5 was an amazing improvement to the base quality. With TH2 Producer you start off with something great and the full version just gives you a ton more options (so many it's actually a little overwhelming).
What I would suggest is...
a) If you haven't already read the very short manual thoroughly. There are many weird and hidden things in the program that if overlooked really takes away from the usefulness of TH2
b) Set up the Overloud Custom head, check out the the various models WITHIN that head (the little red dialog on either side of the head is where you browse that stuff) and use the slider to try some blends (it's two channels so blending the included heads is a huge part of making it sound good). This blending is a different kind of blending algo than traditional amp sims or hardware mixing so it's not like just using a mixer to create a level between the two. Supposedly the amps react to each other in some wacky Overloud voodoo
c) Play with the flyout Varifire control on the right side of the amp head. I find by default this dial is set a little low and a lot of people don't realize it is there. It's a freaky parameter and I'm not sure exactly what it's supposed to be (more Overloud Voodoo) but turning it up really makes the models sing. Definitely worth checking out.
d) Go mess around with the cab settings. Try the different mics and move them around. It changes the tone radically. You can also load IRs (I think you can do that in the Sonar version... in the full version you can). There are tons of options in the cabinet pop up so make sure you read the manual so you know how to access it and what everything does.
e) Mess around with the chain. I find some of the default chains are wack. Like they have pedal AFTER the head. Try putting the pedals in front of the head like you would with a proper live amp set up. You can also use multiple heads in series or parallel or whatever you want if you use the mixer thingy which is a whole other thing to check out.
The presets though are indeed a little weak.
Also as far as the problems when installing the presets there is a specific procedure that needs to be followed. At one point there was a youtube vid posted about how to do this properly. You'll have to google it because I don't have it linked but it was posted many times here on the forum. IIRC a lot of people were having the same problem with the preset packs you are describing.
Cheers.