You did 2 things "not absolutly right" (even if they are not really wrong).
First : never enlarge a video. In other words, hen you DL a movie you should do it in 720*480
Second, if you use a lower resolution according to your source size (let say you you the regular SVCD resolution that is 480*480), then you will need only ONE cd if you do it in KVCD while regular SVCD will need 2 disc to obtain the same quality.
Even in 544*480 you can put a 1h45 movie on a single disc with KVCD. You won't never do that with regular SVCD.
And to return to your test : in 720*480 on 2 disc SVCD turns great, but KVCD would have turn AWESOME
Note : a bitrate is determined by the length of the movie and the place on the disc; It CAN'T be higher in XVCD than in SKVCD for instance.
(bitrate = bit/s = bits divided by seconds...).
Note2 : the resolution in SKVCD is not fixed so there is no reason to tell it os lower than XSVCD. You can do a KVCD in THE RESOLUTION YOU WANT !
Note3 : KVCD
ARE XVCD and SKVCD
ARE XSVCD. By definition XVCD (XSVCD) are just VCD (SVCD) using not regular parameters. And the matrix used by the "K" is far better than the regular one.