Can i use a triple mech and shifter on the double bashgaurd version?

probably yes. From the looks of it the double is just the triple with a bash rather than big ring. In that case you can use a normal mech and either limit the top screw or don't try and shift up into the big ring.

MBR tried to tell me that I should buy a double specific front mech as it'll work better. 'cause a triple front mech really struggles to sift from a 22 to 32. I don't think I'll be buying MBR again for a while.

If you have a shifter and mech that can do three rings, they'll be able to do two. As jon said, use the limit adjuster so that you can't over-shift into the third ring.

SLX 2 ring front mech is intended to give better clearance for wider tyres and is sized to only work on a two ring set up. You should be able to set up a 3 ring front mech to work on a 2 ring set up by adjsuting the limit screws, but you might get a bit of chain rub at each end of the cassette.

I'm running a triple mech, it's fine, haven't bothered adjusting the limit screws, I think the bashguard may physically stop you overshifting, but I've not really pushed it. Chainline seems the same as middle and granny on a triple setup, 22×11 seems to be ok, but it's not normally on my list of selected ratios.

"SLX 2 ring front mech is intended to give better clearance for wider tyres"

That's why I want one

Have you tried an SLX mech and wide tyre yet? My old XT rubs on my Bontrager 2.35 tyre!

ADvantage 2.4 rubs my XT 3 ring front mech (Pitch).

Buy the double specific version mech. The double chainset has a 36t which requires more throw. Its only slight but I tried to use a triple mech and always got rub. Yes it'll shift fine but could never set it up without rubbing at one end of block or other. If you're spending on a new chainset the extra for a mech isn't that much. I got a pretty good deal from merlin.
Shifters on the other hand are fine. I'm running mine with xtr ones.
Oh,and yes clearance is better.

Looks like I need to decide if I want to go for a new chainset before I decide which mech. Anyone with a double chainset miss having a big ring?

awh – if your cranks are ok, just take off the big ring and add a bashring. Try for a few rides and see if you miss it before commiting. I went for 36t middle which is enough for the terrain I ride on that bike.

AWH-

not at all, only really used it on tarmac downhills anyway, but its not that much trouble freewheeling for a bit is it???