The TS-950SDX also uses power MOSFETs: Motorola MRF150s, also run at 50 volts (well, 48 volts, but close enough). That radio is designed for 150 watts rather than 200, but the VRF150 is a heavier duty part. According to Kenwood's literature, it was the first HF amateur rig to use FETs intead of BJTs in the transmitter, and it offered a lower distortion output as a result.
The power supply in the 950SDX is linear style (as opposed to switching) with two different transformers and several different regulators and output voltages: 50v for the finals, plus 15v and several 5v outputs. I think there's one negative voltage for the florescent display tube too.
The transformers account for much of the radio's weight: it's nearly 60lbs. I hope for the 990 they switched to a switching style supply, though with everything else they crammed into it it's probably still going to be pretty hefty.
-Bill
Added:
Oh, derp, the description at the Kenwood link says it does have a switching power supply.