I need to buy a new mech to fit my new Cotic Soul. I’m running 3×9 speed chainset at the moment – Truvativ Blaze. I plan to move to a SLX 2×10 chainset in the summer, but cannot afford to do it at the moment.
Looking at the SLX front mechs on CRC. There seem to be a million different options to choice from. I a bit dubious about much difference there really is:

1) Is there any technical reason one would choose a conventional mech over the standard? I can see the obvious reason if it won’t fit the frame etc. on full sus. But cannot see any other reason other than aesthetics?

2) Is there any real difference between the 2×10 mech and the 3×10 mech? I’m thinking I can just wind the stop screw in if I use it on a 2x chainset?

3) Any reason why I cannot use a LH shifter from the 9spd range on a 10x front mech? I know the rear mech isn’t compatible because of the actuation ration. I’ve not heard of changes on the front mech actuation.

I’ve had a look on the Shimano website, but as usual only half the info is there.

I was thinking this exact same thing the other day! I’ve previously been running a 3x front mech and shifter with 2x chainrings and its not been a problem, my Bfe hopefully arrives this week so needed a new front mech, think I just ordered a 2×9 one in the hope it will still work with my 3x shifters but no idea!

In my head I’m imagining they will all work the same but I think the 2x mechs are slightly more compact as they dnt need to reach the big ring.

2x mechs have shorter bit that does de-railing. The clamp position is not critical on a conventional frame, but FS & 29ers where space is an issue it is.

Oh & top swing ones by virtue of being tucked down lower collect more muck

Haven’t had a close look at the 10 speed stuff but the 2×9 SLX shifter was the lightest mtb mech Shimano did at the time, might be the same’s still true. It also worked better than a 3×9 one- custom shaped cage.