I believe the reactor stove is designed primarily with cold climates inmind due to the heat radiation system is uses, from discussion with MSR.
The whisperlight should be fairly clean stove in operation, but you can make it cleaner.
As long as the ports are clean of debri/charing you should get a clean burn flame when upto temp, ie blue. From my experience its usually priming a petrol stove that makes it soot up, so take a little bottle of medical alcohol or methelated spirits and use a few drops of that to prime the stove rather than petrol. Doesnt soot the stove up, as it burns.
So if your stove is working properly should get nice blue flames and only leaving a small amount of white soot from the petrol on the bottom of your pans. This should wipe off easily. I see a lot of folks try to start a petrol stove before its upto temp properly.
You can also send MSR stoves back to be serviced by MSR for a nominal price. They replace most minor items for free and even some major items. My dragon fly recently had its entire body section and pump replaced for free, when i sent it back due to a broken needle.
If you need the details,let me know..
safe riding and hope to see you out on the road. .. John..