Hiya!
I play the saxophone, piano (Well sorta), recorder, tenor saxophone and I sing quite well

Oh and yes I have dyspraxia and Dylexia!
The saxophone
I will start with. I can play this instrument by warehouse is weird as I can't do that with other instruments? Anyway apart from me being clumsy and dropping my saxophone I find it rather easy. I think the reason for this is as saxophone can only play one rythum at a time I will explain why this is so crustal later on. I do find it hard remembering all the Reid and remembering when to turn up to lessons. I have played it for 4 years and now could most likely teach people now.
The Piano
I have played the piano for 10years now! All those years I never quite could get the hang of it. Sure I would practise but I could never manage two rythems at the one time unless I spent weeks working on a song. I believe this was down to my dyspraxia as if I ever did manage 2 rythems I would have to sit down and practise for weeks! Then my brain would finally process it and I could play the the song easy! I also found it are to find the keys. I think this is due to my cawardanasion as I would always be one key off even though I knew the note I would end up putting my hand somewhere else.
Other Insterments
Well I did try drums. I had the same problem two rythems at the same time! I just could not manage it. I couldn't do one thing with my right hand and another with my left. I also tried to play guitar, but I knocked the teachers guitar as I bumped into it so I never tried again!
I really hope this helps you out and I hope your disartation turns out okay so know how much of a pain they can be :p