Here's my PERSONAL experience from using both of these types of formulations. If you're looking to polish paint - use MEGUIARS' No. 7, or No. 9 for any type of gloss finish as this what they are formulated for. Novus polish is only for polishing ACRYLIC LENSES of cars, motorcycles, etc. If you are polishing a windscreen (windshield), or canopy you can either use Novus, or use Plastix which is formulated soley for clear plastics of this type. Use this GENTLY! It's abrasive and it can scratch paint surfaces. As I said before; your can use Meguiars' (pronounced meg - wires) you'll have excellent results, but you'll have to use it sparingly. Put a small amount of the polish on your cotton swab, then slowly and gently rub until you see a glossy finish form. DON'T SAND!! Unless you've painted it with at least entire can of clear coat. Use 1500 grit to wet-sand your surface. Do this in swirl patterns so that you don't get high and low spots in your paint, or burn through the base coat underneath.
Do NOT USE TOO MUCH! This will make a hazy gunky dull spot on your paint and it will need to be rubbed until it's gone. You'll want to rub in swirl patterns with this so that it will not leave a depression, or a sanding mark in your paint. A little bit will go a long way. Just rub a small spot at a time until you have the entire thing lightly polished to a high gloss all over. It can be done - I've done it this way for over twenty plus years, and this is still the method I use for polishing models, and their painted parts. It's not impossible, or difficult to use to get the results you want without a lot of fussing over it. Let us know how this comes out, or if you need more tips just say so. I hope that this helps.
~ Cobra Chris