I dont see a pooblem with missing out trills. they are just decoration ( but do add charactor) In a piece like a chopin waltz, say minute op 64, you cannot really miss the trills, as its part of the piece. But a perfect example is the inventions. Miss them i say if it is going to affect the timing then miss it. most of them are quaver or seniquaver trills, which wont make much effect missing them! Have you done no 1, my favourite!