For example, on my rig with two 7770's... 390 khash or 440 mhash...
when difficulty was 16 it was about $2.05/day for LTC and $1.75/day for BTC.
Go back to when difficulty was 11 and you can see just how profitable it would have been.
But.. of course now that difficulty has gone up, immediate term mining is now favoring BTC in most cases, but if you feel that LTC/BTC is going to improve then you'd still want to mine LTC as if it goes up to .01 or .015 sometime then it be well worth the while to mine now (or even better to buy some coins).
I am curious what the BTC halfing/asics will do though.. it could get interesting or ugly.
at least two big swings (both ways) in bitcoin price if asic's hit this year