From what I've read on here, the standard (non-Recon) Stryker is best left unbuttoned to maximise spotting in-game (can't find the threads on this atm).
In this thread @Vanir Ausf B lists vehicles better buttoned for spotting http://community.battlefront.com/topic/118276-to-button-or-not-to-button-spotting-the-enemy/?tab=comments#comment-1583995 but doesn't mention Strykers
What say you re the Recon-specific M1127 Stryker with LRAS3? Buttoned or no? Is the LRAS3 system best used stationary, and perhaps difficult to use on the move (or not)? I could perhaps see when stationary, M1127 might be best buttoned to use LRAS3 effectively? But TBH I ain't going to be parking a Stryker anywhere as a primary OP: I'll be dismounted the Scout team and doing that on foot, leaving the Styker in concealment (if not cover)......
The topic of crew vulnerability when unbuttoned is moot here (and yes, obvious in a modern battlefield): I am solely focussed on (long distance) spotting please.