There are quite a few small mills with this sort of lever feed, friend of mine has a Sixis 101 where they are on all axis. They were used for all sorts of things where a quick or repetitive action was needed much like a capstan or cut off slide on a lathe rather than general feeding. But generally for lighter cuts in non-ferrous materials.
Say you want to cut a hexagon on the end of a part. Fit a rapid indexer on the table and adjust so that each face can be cut in one pass. It is then just a two lever job to cut-spin the indexer-cut- spin etc. So ideal for small batches but if doing individual cuts then you would use the handwheels.
Your backgear speeds sound more usable for the cutters you have. What is the tooth count and width? Should be able to work out a feed from that which will keep all teeth doing something.
Eg if we said 100rpm and it is a 30T cutter then 0.002″ chipload per tooth will be more than the 0.001″ runout then that is a feed of 0.060″ per rev or 6″ per min. Assuming the leadscrew is 10tpi then should be quite possible to wind at that rate which is one turn per second.