I have an Alitech, it's a pretty sweet piece. There are lots of customization holes on the linkage connectors, so I think it should work fine with a Letsla. I don't have need of a Letsla in my case, but it seems like it would help clean up the slop on the tranny end. As far as shift cables, a new set of OEM ones will do you good-- over time the gray plastic sheaths on the ends will crack and break, giving the cable more slop.
* There's slop in the OEM shifter housing (mods can remedy this somewhat, as does the alitech)
* There's lack of adjustibility in the OEM shifter housing (alitech addresses this)
* The OEM cables deteriorate over time (I think there were 2 or 3 providers, as well as a company that will make custom ones for you for about the same price)
* The linkages on the transmission can have slop (I think the letsla also changes the feel of the shifts with adjusted pivots, IIRC)
You can definitely start with the lowest priced option and work your way up the dollar chain, and stop when it's good enough.
I'd first check your OEM shifter cables and make sure they aren't substandard. Replace broken parts first.