Gear

If you liked Mantas aside from the weight then SLs would be an obvious alternative, though you could still get a fair bit lighter (sticking with Scarpa, which is a good idea if the existing ones fit well, you could get Rangers).  Lighter will probably be a lot less stiff which might or might not be to your taste: when scrambling a stiff sole is a two-edged sword, making it easier and less tiring to stand on small, positive holds but on the other hand making "smearing" friction moves harder and your feet are generally less mobile and it's harder conforming to sloped surfaces.

I prefer shoes these days.  On the one hand there's less ankle support and protection, but on the other there's a great deal more ankle mobility and they're far less tiring to walk in.

Pete.

I think the Rangers are just too flexible for scrambling

Why?

Last scrambles I did were in a pair of Tevas.  The flexibility meant that they conformed to the rock surface and gave me far more friction than I'd have got with a stiff boot.  Stiff is good for small, positive holds where you have an edge or toe supporting everything, but for general friction the softer the better.  In practice routes vary so a compromise may be best overall.

Pete.