[GeorgeTH]

From my limited experience with free sites (my TGP submissions go back to 1998) I can tell you about free sites in general:

1. you get less traffic per site (I think the max. I get is ~5k/listing from link sites considered to be 'rather large'), whereas TGP traffic can be easily 30-100k/listing.

2. listings on link sites are staying longer on the list (typical TGP is 1-3 days on front page, unless you make it onto sombody's 'Top Gallery List'). Niche submissions on link sites can be on the page for up to 2-3 months (depending their niche).

3. Conversions should be better since LL are trying to get a lot more search engine traffic and usually don't skim your link (= send a high percentage to trades).

edit:
4. just looking at my stats - my TGP galleries are getting a lot of traffic from sites where I don't want to get traffic from (like Sexocean.com, p0rno.org, etc.)! There are just too many CJ (circle jerk) sites who simply harvest links of other TGPs. They usually send tons of unproductive hits you weren't looking for.