But by converting, you are losing ressources overall.. I can understand getting a few early flamers and mines early, but once you get a luchs id be more temped not to convert.
I think early kubel pressure is best way to open atm. I like to follow with flak HT, medic truck, then Oswind. One of the great things with JLI is they dont need muni sinking into them unlike lots of other inf.
In the new patch, its not a bad thing removing conversion, because now they have full ressource income. Only 'restriction' is not having caches, which isnt the end of the world.
You definitely don't want to convert munitions for a very long time, but doing it to get specific upgrades when you need them is useful. (Especially since outside those upgrades you don't really need muni at all.) In the late game too it's also good to convert muni since you'll be popcapped and begin to float fuel anyway.