Maksutov,

Granted dust will reduce and scatter - but so what if you lose 10% of the light, 0.1-0.2 mags is not worth getting worked up about. The owner of a beginner level instrument should not be encouraged to start taking it apart. The Dawes limit is not a useful concept for a backyard telescope - theoretically a 130 mm mirror could split 0.9", now find one that does.

On the subject of aluminium - IUPAC recognises Humphrey Davy's third attempt to name the element with recognition that the ACS has differed since 1925. Personally why "alumium" never caught on I'll never know... (H Davy's first name for the stuff)