Re Eros: I recall one report by a newbie who was paying above standard rates all over the gulch
http://www.costaricaticas.com/phpBB2/viewtopic.php?t=7848&highlight=eros. They pay taxistas commissions for bringing gringos there, so if you come in a cab they may try to pass it off to you and charge significantly more. Has anyone heard reports of them trying to charge $60 to anyone who didn't go there in a cab? If you directed the cabbie there, I'd tell them that and insist on the regular price or, better yet, tell the taxista to take you to IDEM or Tin Jo and just walk to Eros (its directly across the street from IDEM). If for any reason they still try to stick you for inflated rates, tell THEM where to stick it. I don't think their volume of business is so great that they're going to turn away a gringo customer just because he isn't so stupid as to pay $60.
As to chica quality, from what I've seen it does tend to run in the 5-6 range at best as Mas Chicas suggests,
BUT you never know. I usually poke my head in there whenever I go to IDEM just to see what is around. I only sessioned there once a few years ago, but the last time I was there I saw a few chicas that were much nicer than usual and I was tempted (decided to check out IDEM first and ended up not going back to Eros). Again, like I said before, don't write it off as you never know and you might catch it with a rare treat. BTW, Zebra reported having a good session there recently.
As for IDEM: I prefer IDEM because of the Bar atmosphere where you can take your time making a selection. I always feel pressured to decide at Eros (just some vaguely uncomfortable feeling when I walk in there) which might also have something to do with why I usually don't stick around there for more than 30 seconds. I would concur with 4Reel as to the best times to go 5:30-7:00PM to get there after all the girls have arrived but while they are still fresh and between 10:30-11PM so you will have a full hour before they close at midnight sharp. IF you get there at 11:15PM like Orange did, you best bet may be to hit the girls up for numbers or some moonlighting work back at your hotel.