The problem is that size and weight are not the only criteria. I am 5'12" :), weigh about 240#, and have a 38" waist and 30" inseam. I can fit into rides that people shorter, lighter, and thinner than me have problems with (Scooby's Ghoster Coaster at PKI comes to mind). On the other hand, there are rides where I can't fit at all where people who are taller, bigger, and heavier than I am have no trouble at all (such as King Cobra at PKI). Whether you can fit or not on a particular ride is going to depend on some very specific relationships. I've seen people have problems with Flight of Fear not because their legs were too long or their waistlines were too big, but because their feet (or at least their shoes) were too tall.
The answer is, you won't know unless you try. And unfortunately, there is no test seat. It does seem to me, though, that fewer people are being turned away than back when the ride had shoulder bars. Only thing is, now it's different people...!
--Dave Althoff, Jr.