I think your BitX40 had the best sounding audio of them all, the 450 next, and I was astounded at how noisy the 817s receiver was, and to think I always wanted one of those, not anymore.
After my initial troubles with a broken L2, the BITX40 is hearing well and making some surprising contacts. Here's a little comparison video of the received audio from the BITX, the FT-817, and the FT-450D.