Coming from someone who started in running, then made the jump straight to tri's and had to pick up cycling and swimming along the way. I've raced everything from sprints to IM and they all differ in your approach, training, speed. I'm maybe a MOP'er in tris, certainly BOP in the cycling world. Here's a few things I've noticed:
-Yes, lots of guys who have really expensive gear who ride at 16 mph. its very easy to spend lots of money and look fast when your bike is racked and in transition.
-Being aero does help regardless of speed. If you have an 8hr IM split on a tri bike with a 808/disc set up it could have been much worse with a heavy alum road bike and open pros. Since we can't draft, its up to you to hide from the wind or power through it.
-If you haven't tried a brick work out, do a FTP test then run 6 miles as fast as you can. That would simulate a oly tri which consists of a 40k bike and 10k run. It can be eye opening.
-Doing a brick work out with a road bike vs tri bike is night and day difference. My road fit ruins my legs for a run, where as my tri fit allows my legs to feel "fresh" for the run.
-For the long course race training, its all about staying in zone 1-2 of your HR for most of your training and you build aerobic fitness, so most of us will ride relatively much slower than the roadies.
-IMO, riding a tri bike in groups rides is pointless and scary. Thats why i only ride it on my trainer/solo rides.
-Some, like my self, are looking to get in with the roadies however it can be intimidating!
We're not all bad!