Let's put it this way, NONE of the RAAM riders would still be riding after the 2nd day of the TdF due to imposed Time Limits. Where as 95% (IMO) of the TdF riders could finish RAAM. (Do a search, I follow RAAM and am impressed with the challenge. I was posting about it and getting flack from Botto as he regards it as the world's most boring race)

As far as a TdF rider beating Jure Robic, I think more than a handful would have the capability. (By beating him early in the race and crushing his spirit. Guy is never behind at the timing stations)
Of course it would take a committment to a modified training style for this event and the $$ would have to be there to entice grand tour riders.