I've shot both a 365 and an XL that had the manual safety. The width of the levers is workable for me but the placement that I have more difficulty with. If the shelf of the lever was moved just a little forward, that would be great (for my hand size and shape, at least.)
I suppose this is well within SIG's manufacturing capability. I'm not sure though if there is enough demand (for manual safety versions) right now to entice SIG or an aftermarket parts maker to invest in production.