I don't understand why you would want to ditch either the K-x or LR3.
LR 3.2 totally supports the K-x RAW files, and does an EXCELLENT job rendering K-x images. I have been very impressed with LR3.2. Using LR3.2 as an image manager and RAW convertor makes perfect sense.
If you want one-way tethering to work (ie take photo, have it turn up in LR3 automatically), rather than two-way tethering (view camera images plus control camera from LR3), it may be possible to have one-way tethering work via using an eye-fi card and LR's 'monitored folder' feature.
Either way, Pentax is said to be working on tethering support for the 645D. It may then trickle down to other models like the K-5 and perhaps even reach entry-level cameras like the K-x.
Originally posted by Miguel lacking total tethering capability is far more of an issue, and that's the camp Pentax falls into
That has by no means been established by anyone. The capability may be there (ie good PTP support in the firmware) but the applications just haven't been written yet.
Originally posted by Miguel BTW, you can tether some current Olympus and Sony DSLRs.
But not in LR3, which the discussion here is all about.