We chose to be very conservative with doppler and ultrasound use because it is still very much an unknown, and as long as things are progressing normally, it is not necessary to the continued good health of the baby. If something is wrong, usually doppler by itself is not going to give you enough information, so really (as far as I know) it's just for fun 98% of the time. I'm sure there are situations where frequent monitoring can be justified, I just can't think of any.
We did use Doppler once already with this pregnancy....I had some spotting and some date discrepency, and a quick check for a heartbeat gave us reassurance on both counts. Now, unless something were to happen to convince me it was beneficial, I don't intend to use doppler again until labor....I do allow the mw to use it in labor pretty much as she desires...I feel like in that context the benefits outweigh the potential risks.
I'm totally in favor of using a fetoscope--don't see any problems with that, and if you've never heard the baby's hb via fetoscope, you are missing out! It sounds like a REAL heartbeat, not the weird horsetrot sound the doppler makes! It's really cool. Most of the time, a fetoscope can easily find the heartbeat from 20 weeks or so. They make long tubes so that mom, dad, and siblings can also listen. Some docs don't really know how to use a fetoscope (because it's considered old-fashioned and outdated) but any midwife worth her salt ought to be able to use one!
Another issue with doppler and ultrasound is the potential, unknown risks....I've recently read plausible articles posing questions about a possible link between increased (excessive) ultrasound/doppler use and autism. Of course more research should be done, but it makes sense to me that it is not a technology that should be taken lightly, to be used at the drop of a hat, for entertainment purposes or for anything less than a specific, well-defined reason, in which the benefit outweighs any potential risk.
Just my :, YMMV, etc...