While I can't comment on the relative difficulty between 10 man lei shi and ambershaper (25 man makes use of an extra tank to ease the encounter), your group setup is VERY strong for Ambershaper. You literally have 3-4 multidot classes for the ambers, cleave for monstrosity->reshapen life, and good singletarget burst from the hunter on the reshapen target.
Lei shi is probably a tiny bit easier in the sense that you don't need to wait for everyone in the raid to learn exactly what to do in all situations inside the Reshape life. But they are fairly similar.
While it's true that Lei Shi has higher dps/hps requirements than Amber Shaper, I'd definitely say Lei Shi is a lot easier. Amber Shaper is one of the hardest 10 man fights in this tier, while Lei Shi is really simple imo. So if you're guild isn't noticeably behind on gear, I'd say go for Lei Shi.
anyone care to share their tactics on the scary fog stacks? give a few tips and what not?
We used 3 people: 2 mages and a lock. All 3 start outside, then at 4 stacks they rotate in; 100% debuff uptime on the boss. The mages went in and dropped their stack before going out and restacking, the lock got out in time to refresh it. We blew hero at 40% because the lock was around 20 stacks there.
I haven't seen another 10m do it this way, but it worked for us.