I left MS stack (not a big fan of Windows), so having really cross platform IDE is a big win for me.

Can't say anything on TS - but AFAIK it's mostly syntactic sugar on JS, no first class IDE on non-Windows, no pub (dedicated Dart package manager), no native VM (I'm also doing server side on Dart recently) and still it's possible shot your foot just like in JS - saying all that - I will have to really try it out.