I had my beloved K50 starting to develop the Black frame issue, was looking around and found an incredible deal on a K3 combo with low shutter count and jumped on it. K3 is amazing camera, very quiet, fast focusing and decisive too. K3 noise when compared to K50 is different. K50 has best picture quality up to ISO 6400 but K3 will use only till 1600 (at least for my liking).
I am still using the K50 with an AA adapter, no issues. Adam suggested the new PLM lens which I will eventually buy and keep using the K50. My 11 yr old son will get the K50 while I chug along the heavier K3 kit, good combo for hiking and bird watching.
So like others mentioned if you want a second one, get K3 or K3-II depending on need for using Flash. Or else get the K70 with extended warranty for peace of mind.
Even better save money and get the K-1