Rick (K2XT)
I certainly agree that it pays to do your homework in terms of optimizing your choice of the many good radios now available. For example, I routinely use the flexible TX/RX antenna switching in the TS-890S, as well as the LF/MF exciter outputs, and the per band/per mode power control/limit for both tuning and operating alongside an LMOS amplifier. The very clean transmitter and excellent audio/ALC were also important factors. (As an aside I see the TS-890S still sits at the top of a couple of the Sherwood columns, if that matters).
So far as upgrades go, there is definitely something satisfying about a little box, rather than an upgrade key! The roofing filters in the Kenwood are user accessible and the other night I plugged in the one option available: a 270 Hz CW filter. The result was a worthwhile gain to an already excellent CW radio, with DSP bandwidths of course available down to 50 Hz width.
Having designed quite a few receivers I'm quite agnostic about architectures, although I think the high-IF sampling of the FTDX101 or 10 is a good choice right now. The problem I have with the TS-890S is that it works so well on the development bench, I almost need another one for physical convenience. (The hybrid SDR main receiver and fast, parallel path display SDR give my FFT spectrum analyser a run for its money). Having used an FTDX101 I'm impressed overall but not greatly taken with the ergonomics or display. However, I'd compromise at the FTDX10 level except for the fact there's no LF/MF output. But without that imperative, I'm sure you'll enjoy an excellent radio.
73, Peter.