Tesla will likely be discontinuing the 14-50 Corded Mobile Connector. It's currently listed for $520 while an HPWC costs $500 (either for hardwired or 14-50 connection).
We have been using the 14-50 MC to charge our X 100D, with a 14-50 outlet installed next to the X's charging port.
Recently we had our signature black HPWC installed, and because it didn't come with the 14-50 cable, we had to have an electrician run a short line from the 14-50 outlet inside the wall to the back or our new HPWC.
If we'd had the option for a 14-50 connector on the HPWC, we may not even have needed an electrician, because installing the HPWC is pretty simple - a few bolts into the wall, and then setting some dip switches for the amp setting (which should default to a 50A circuit for the HPWC's with the 14-50 cable).
Though, because we did have an electrician install our HPWC on the existing 14-50 cabling, the electrician was able to upgrade the breaker for that line from 50A to 60A, so we get 48A of charging through the HPWC, 20% faster than what we were getting with the 14-50 MC.