Anyone have any advice on this?
The short answer - in the form of an opinion:
If you currently have a paid-off GPU mining system sitting idle it is more profitable to use that.
If you do not currently have a paid-off GPU mining system sitting idle then it is much more profitable to just use that money to buy LTC.
I ran a gamble and bought two used 6870s and a larger PSU for $375 total 2 weeks ago and have mined 50LTC so far. This means it'll be about 30 weeks of mining before that expense is paid off if the value of LTC and the difficulty don't change too much (or more likely that they both increase and cancel eachother out to some extent).
I decided to do both since I have money to spare - I bought about 500 ltc around $0.55 a piece and bought some used cards. I think it will work out OK for me. I did decide though that it's not worth it for me to pay for a new dedicated rig.
YMMV