hi! i've got both, and use both... both very well made indeed and both have their pro's and cons... the eagle vision is super simple to fit, offers great quality footage - i've got all the time in the world for what they do. cons - it can be a bit bulky compared to the sideshot set up, but is way easier to fit and swap between guns.
sideshot however feels the sleeker of the two, offers great footage too - but is harder in my own opinion to swap between set ups...
like i say, both have their pro's and cons - i still use both of mine regularly! end of the day: you won't be disappointed with either!
hope that helps,
james