a couple of years ago, on my virgin trip to the sexier side of LOS, the tour guide did show us that place. it is exactly what you've describe - opposite alcazar cabaret. i beleive it caters to mostly tourist as i see some japanese and chinese signs that says no camera allowed. the second floor is for breeders, while the third floor is for PLU.
i liked this place coz it is just shows. i don't know if you can off the boys there since there is no "gogo" to speak of. but hey this is thailand.
but if you're looking for the biggest - like the 11 inches mentioned above, then look for number 1 of future boys in bkk. i beleive you'll get more luck in bkk if you want to see the merchandize first.
on my last visit to pattaya, i only know of throb and splash having shows, but there was no big cock show, only swimming acrobatics and drag show.