Anybody here fluent in both Dvorak & QWERTY?

I learned QWERTY first, in 8th grade, over 40 years ago, and was
typing about 50 wpm.

Six years later, I abandoned QWERTY and switched to Dvorak,
self-taught, with nothing to help me make the switch other than
modifications I made to a QWERTY typing manual. (This was long before
there was typing software or PCs with software-switchable keyboard
layouts that help with that. Smith Corona made me a dedicated DSK
electric typewriter.)

I found switching to be one of the hardest things I ever did. 
Frankly, I never would have switched if I'd known how hard it would be
*for me*.  Every time I stopped concentrating, I'd revert back.  It
took me months of daily practice before I recovered my QWERTY speed
and then got faster.  Most people seem to be able to be trained to
switch easier than me.

Next fall I'm entering a medical transcription training program where
at times at least it will be very difficult for me to be able to
touch-type in Dvorak.  I'm trying to learn to become fluent in both
keyboard layouts, using Ten Thumbs software, so I can use QWERTY when
I absolutely have to, and Dvorak when I can for better speed and less
wear and tear.  I started about a month ago.

This is proving to be even harder.  Though I practice with both
keyboards daily, as I'm gaining fluency in QWERTY and clearing 40 wpm,
I start making more QWERTY key errors when I switch back to Dvorak,
and my 70 wpm Dvorak speed suffers.

Also, while I can QWERTY 40 wpm plus and gaining, IF I'm typing
prepared text as in typing software, my ability to think and type in
QWERTY as in typing this post is horrific, Dvorak-key error laden and
probably net of 15 wpm... this bodes very poorly for my ability to do
medical transcription in QWERTY, because one has to listen and
transcribe and can't think about the keys he's typing.

I may have to abandon Dvorak and just go QWERTY again to gain speed
and accuracy in QWERTY, but I hate to do that.  Any suggestions from
anybody who has fluency in both layouts?  I've heard there *are* who
retain fluency in both.