We've just started using RADSpell. Overall we're very pleased with it, but have noticed a couple of idiosyncracies:
1) Non alphabetic characters, including spaces,
inserted into a word cause problems to the spell checker. For example,
when checking "m,uch" the spell checker will allow the "m," and suggest
an alternative spelling for "uch". There is
no possibility of highlighting the whole word and overtyping it. In
this case you will need to "Ignore" the word, make a mental note and
overtype the word after the spell check is complete.
2) The spell
checker flags repeated words, but indicates that there is a spelling
mistake. For example, with "he had had an intra-abdominal haemorrhage"
the spell checker will flag the second "had" and suggest the
alternative spelling "had", which is clearly confusing.