This cheap Radio Shack model (manufactured by Sonic Blue/Go Video) handles VCD, SVCD and CVD without modification. I was mainly interested in seeing if it could use KVCD MPEG-1 templates. I did not test MPEG-2 templates because I'm interested in lower bitrates, and regular SVCD and CVD is fine for me for MPEG-2 (I use DVD2SVCD for those conversions). I tried a low bitrate CVD, and it looked bad, so I really wanted to get one of the KVCD templates working.
KVCD vs. Cinevision DVP-650
Since I am still very new at all this, I used Red-M's
Guide to Creating Good Quality KVCD's (x2) v0 as my base method, then for my subsequent tests only re-encoded the video, muxed and authored my 5-minute clip on a CD-RW (Nero burn). This is because lower-bitrate audio seems to work in all scenarios on my player. (I encoded my audio @ 160Kbps CBR, and reused it for each test clip.)
I first authored each clip as VCD, and if that didn't work, remuxed and reauthored as SVCD.
KVCDX3 528x480 VBR MPEG-1
with VCD Header - No
with SVCD Header - No
KVCD 352x240 VBR MPEG-1
with VCD Header -
Yes!
KVCD 352x480 VBR MPEG-1
with VCD Header - No
with SVCD Header - No
Non-standard lower CBR xVCD 352x240 MPEG-1 (@ CBR 1048Kbps as calculated by MovieStacker)
VCD Header -
Yes!
Looks good
Standard CVD 352x480 VBR MPEG-2 (@ VBR 1048Kbps)
with SVCD Header - Yes (this was expected)
Looks bad (not expected

)
My conclusions:
KVCD/xVCD seems to work fine, as long as the frame size is
only 352x240 (accepts CBR and VBR MPEG-1). KVCDX3 MPEG-1 does not work. The SVCD authoring trick does not seem to work. On the positive side, audio on KVCD/xVCD does not have to be 224Kbps.
If decide to test MPEG-2 using the SKVCD/KVCDX3/KDVD templates, I'll post my results. My inclination is that KDVD should have no problem, because it should be the same as standard CVD.
Thanks to Kwag, Red-M and all the hard workers out there!