simplesimon - I think for solving ability I'd advise, become very old.
I have set a few puzzles and got somewhere close to getting a Listener idea through (this was ages ago!). That experience pretty much put me off setting puzzles... unless I'm really interested in something and I'm prepared to waste a lot of my own time on it. Anyway, my advice (from very limited experience) is -
Don't get involved in on-line spats with crossword people - especially setters, because they are a very close-knit group and really stick together.
Don't EVER criticise mathematical puzzles (just about everyone at the top in crosswords has a maths background... I know... but it's true).
Seriously though - I hope you get your ideas through - I think the crossword grid is a marvellous little area of creativity but, sadly, very undervalued (and I look forward to tackling one of yours quite soon).