That's good getting the SMP going, BAP. If it's going right, that'll be a marked increase vs. singles. The only time I've ever used the -configonly flag/command is from DOS and I don't think that's an environment you'd find all that friendly or useful at this point. If you want to change something just as easy to do it from the GUI interface. Or in the case you have just done, I'd re-run a whole new setup in a different home or directory or folder and have that for SMP, while keeping the singles where they already are and simply dormant.
I wish someone would leave wrapped toys in front of where I live, I'd certainly unwrap them quickly. That'll be a likely even bigger boost than the one you've just done, something to look fwd to once you can get to it. It might not go perfectly the first try, as Micro will attest, but that's half the fun once you get beyond the urge to throw stuff, lol. 
We've all been there.
| 