I did RAIN a couple of years ago and I'm sorta thinking about doing it again (though I don't think it's enough momentum to make it happen). While I think I only saw one other toe-clipper the whole time and I got a few comments (but that's *my* attitude - I take it as a compliment when somebody says 'wow! sneakers and toe clips on a hybrid!' - duly note it's an aluminum "hybrid" with reasonably quick wheels and road tires - basically a road bike with flat bars) , there was a reasonably wide range of people doing the ride. Some were really racing it - a lady in my club who was the first woman in who wasn't on the back of a tandem (and she was 53, thank you very much... but she basically didn't get back on the bike 'til THursday) was 30th... I was 300th :-) I stopped and got in line and ate lunch and everything :-) I did the "bus sag" thing 'cause I was on my own and that worked out fine, since (to my surprise) the bus was at the stops when I got there so I could dip in and use its rest room and get another hit of sunscreen and that sort of thing. THen I got to hang around a cooler of drinks and wait for everybody to come on in.
I enjoyed it - rode with informal groups some of the time, by myself some of the time. It's definitely "real" - but you don't have to be competitive real to do it.
Most people told methe hardest part was around Indy, where there's traffic and you have to pay attention and you know you still hae a LOOONGG way to go. That was sort of true but the weather was so good that it simply wasn't that long a ride.