My hands get all red & blotchy when I use Best Press/sizing & I seem to be developing a respiratory allergy to Niagra starch so I plan to go back to mixing my own starch solution.
I use probably close to a whole bottle of Niagra spray starch with every quilt & it hasn't harmed my iron in any way, shape or form. My ironing surface is another issue entirely. I either have to toss a sheet over the ironing board (since the cover isn't washable) or else I take a damp rag & wipe it down when I'm done for the day. I know some people say they iron freezer paper to the surface of their ironing board, but I could never get the hang of that with larger cuts of fabric; the fabric was always slipping around on me. However, that works great if I'm just pressing a bit of applique, touching up small pieces or pressing seams.
If you ever do feel like you are getting starch build up on your iron, just a wet rag/towel should be all you need to get it off. I should mention that I do not have a Teflon coated iron. I don't know whether that makes any difference.