Alex: check the little USB logo (the pitchfork image) next to the port: USB 3.0 will have an "SS" in front of that logo, the plastic blocker isn't always blue. On some laptops you'll have a mix of 3.0/2.0 (the toshiba I'm typing this on has 2x 2.0 and 1x 3.0, so I have to mind which port I use for what). Also important is that USB 2.0 works fine with the default self-installed drivers that windows sets up but 3.0 invariably needs the actual chipset maker's drivers to work (otherwise it behaves as 2.0), which might require a manual install.
Fox: Bintel had pretty decent deals on ZWO cameras round the end of 2016 when we needed one for a summer project, round 190 for the 120MM-S (monochrome 3.0) from memory if you want to hold out for a sale. The high speed USB is definitely the way to go: on a bright enough target (eg Mars is bright enough at opposition from memory) the extra framerate is really good at freezing the atmosphere (what you want for lucky imaging planets). What I'm talking about isn't 60vs30fps, because the real strength of these cameras is their arbitrary ROI (region of interest) capability. You define a box of the sensor around your target and the camera only reads those pixels, which it can do much faster than polling the whole sensor. With good tracking and guiding you can get a nice tight ROI and 200fps is possible with the standard software (we saw 500+ with custom interface).
At that speed you see the higher order contributions to wavefront error from atmospheric seeing though, so a scope much bigger than yours will not always give you better images: on a 16" LX200 we could actually see the sag of the primary over its triangular support on a star image.
My suggestion would be: ZWO USB 3.0 camera of your choice, avoid barlows (altogether even, but especially new ones) and start on the moon (big=easy targeting, bright=max framerate) and your current scope. Use smaller ROIs to push up framerate on native prime focus magnification until you find the limits of the camera combating the seeing, then if your pixel scale calculation shows you should be able to see finer detail consider barlows, then if the light runs out buy a bigger lightbucket.
Big (amateur) reflecting telescopes have a hard time matching with extra photons what they lose to good refractors in PSF quality, and the bigger your aperture the more you "see the seeing": at a good site the isoplanatic patch or size-of-atmosphere-that-only-causes-image-motion (no ripples) is rarely bigger than 30cm, so even an 8" SCT is pushing it unless you live at Siding Spring. Plus all the far-apart elements don't do you any favours with scattered light on a bright object like a planet (for deep sky much less of a concern, then diameter wins the day) - smearing out details the aperture should mathematically resolve.
For reference: Last year we chucked our 120MM-S behind a very nice Tec 140 (f7) and pointed it at Saturn, albeit on a **** mount (I had to manually track the target with the controller, for 3+ hours) and doing ourselves no favours with a 3nm Ha filter. I think we managed about 80fps and it was quite blurry (~30 degrees elevation, terrible atmospheric dispersion if we didn't have the filter). Meanwhile next door said LX200 0.4m f10 flying Canon's super high ISO camera with no filter was about the same image quality, albeit with more pixels covered thanks to ~3m extra focal length. I never saw the other team's raw data but from the screen displays of each setup I wouldn't pick the big SCT over the refractor, I'd just point the thing straight up
