Blindly claiming that an unfiltered scope will "lie" fundamentally misunderstands: 1. the phenomenon of antialiasing, 2. the sampling reconstruction theorem, 3. oscilloscope functionality, and 4. ignores if not outright denies the option of equivalent time sampling.
The sampling window jitter limits how fine an equivalent sample rate you can achieve; this is usually in the single digit ps, so you can push 10s, even 100s of GSa resolution on repetitive signals.
How much do you pay for a 150MSa ADC? Not a few bucks I'm guessing. Seems like a damn shame to throw away that 500MHz bandwidth (or whatever it is). After the front end and all, you're probably not going to want to actually shoot for that, but even an order of magnitude difference is easily achieved (i.e., 200-300MHz instead of 30). Wouldn't it make sense that your front end, and your timing generator, are equally high performance (costly) as your ADC?
Tim