I haven't done anything with the MPX yet, so I don't haven't pics. But I do like the AR ergonomics. If you shoot ARs a lot , there is zero transition training. The charging handle, mag release, bolt release and safety are all AR. And the MPX has an ambi safety and bolt release. It is also easier to add lights and optics. The back up sights are nice as well. Once I add the stock, some mags and stamp, I will have $1700 in it.
As for the PDW, I like the HK style charging handle better than the AR. It just feels more natural to me. Pricewise, I paid the same amount for the MKE K as I did the MPX. However, once I added the tri-lug, the compliance parts and the stock, I was in the 1700 range without the stamp. I had to replace the ejector spring with a HK factory spring to get the weapon to function 100%. Once I did that, I haven't had any FTF or FTE. On the plus side, the MKE functions perfectly with the cheap ATI mags. Shooting the MKE in the PDW form is a dream. Very little recoil. Very accurate at its intended range.
The new MKE come with the tri lug already on some models. So you won't that added expense. On the other hand, the new MKEs are in the $1700 range compared to the $1200 range of the original imports. Add the stamp and stock, you will have a 2K firearm. Keep in mind that my experience is based on the MKE clones. You may have a different experience with the other clones on the market.