I had a ball building my K1 Transceiver. It has worked out very well, and has a fantastic receiver. My only issue so far is that the transmit power folds-back aggressively. If the SWR is high, the power will immediately drop back to 0.5 watts, remaining at that low level. As a consequence, some of my automatic tuners will not work with the K1. With that in mind, I purchased the internal tuner option earlier this year.
I finally started putting the kit together, which is very straight-forward. With about 90 minutes into the process, I have all the parts except the inductors and connectors installed. As with all the Elecraft kits, the inductors need to be hand-wound. These are pretty small/simple, so that’s not a big deal, but it will probably take me another 90 minutes to wind the 5 cores and install them.