Usually positive. Called colour sanding and it normally will level any irrgularity in the surface and provide a good tooth for subsequent coats. One issue is to make sure you can give your whole bike an even treatment. Which probably isn't possible so you need to plan your paint schem with the different surfaces and transitions in mind.
I'm certainly interested if there are high gloss products with low toxicity. So far haven't heard it, so my education may be incomplete. The dangerous problem appears to be that many people assume this is normal product one can finese, while it can cause permanent damage with one bad decision. That could also be old thinking. It's always possible for one person to have the physical resiliance or the fortunate convergence of circumstances to avaoid a dangerous exposure. The question is whether that means the practices they used were safe. Perhaps the safe part is some part of the formula we don't know about.
The other issue is how much does it take to be safe. I have a friend who sprayed this stuff for a boatyard. All they had to do was use air supplied by a branch in the compresor line. Would that be enough? I don't think it is a recognized system since the compressor air is contaminated, but on a risk assessment level it's a whole lot safer than risking a single use exposure that causes lifetime ashma, or death.
Personally I can't see the point for bikes. Touching up a 60 foot catamaran is a big job, repairing a bike, is a nothing. I sure depend on my lungs a lot more than the average person why would I risk them just to have a coating on my bikes that is the equal of the best industry can produce. Sounds like a bad trade.