I'll throw my two cents in.  Assuming that you don't want to save the
components you are replacing, I would advocate the dry thermal rework over
chemical or microblasting.

When you do the chemical stripping, you have a waste stream to contend with
and chemical exposure to the operators. By their nature, urethanes are more
chemically resistant (than acrylics) and require more aggressive agents to
remove.  Second, you will have a perimeter area around the device where you
have a fringe of coating that has interacted with the chemical stripper.
Is that combined material OK?  Is it corrosive or conductive?  Will it
cause softening or attack of subsequently applied coating?   How smart is
your chemical?  Does it magically know to attack only the urethane of the
coating and not the urethane or acrylic that is in your solder mask?

For the dry rework, you only have minimal smoke involved, and a simple fume
extractor, as we use for soldering fumes, works well to protect the
operator from any agents in the smoke.  It is much quicker than chemical
stripping and the pads clean up fairly well.  Use of a hot gas rework
station or proper rework tools minimizes the thermal shock to the board and
pads.  Now, if the undersides of your components have coating underneath
cementing them to the board, you have another situation and you will
probably have to chemically strip that coating anyway.

And this advice is worth every penny you paid for it....

I now brace myself for the two dozen automated out of office
responses.......

Doug Pauls
Rockwell Collins

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