In my experience, with 3e characters at high levels (with little/no multiclassing) characters would have an easy time making saves targeting the Good save, but very rarely make the save targeting the Poor saves.
Multiclassing well can either make saves abnormally better so that even poor saves aren't a drawback. Poorly planned multiclassing can makes saves abnormally bad so that poor saves are a near guaranteed fail at high levels.
In my experience the higher the level got, the more buffs were up to enhance attributes, the luck oriented buffs were up, the prayers, protection from evils were up, death wards were up, and all of these were often enchanted onto personal items ASAP, so even on their "weak" save, or saves, they rarely failed. By 20th level it was not uncommon for the PC's to have a typical +10 (and often much, much higher) to all of their saves due to all of these spell effects and stacking rules. Throw in immunities and save bonus' from many of the PrC's and it gets very disgusting.
It was bad in 1E and 2E in this regard, but 3E was much worse. Mostly, I think, due to the inherent magic item proliferation, followed closely by the stacking rules.
All of which does not exist in C&C, so C&C is definitely much more "challenging" since PC's can actually *GASP* fail and die. Granted, there are reasons people don't like that, but there are plenty of ways to avoid dying in C&C, you just have to work towards it, Globes of Invulnerability, Death Ward, the various "buff" spells, etc...
So again, if the players fail to properly prepare and defend, its their fault. Besides, unless its a TPK, you then have Raise Dead and the like to fix the mistakes. Or you can take the opportunity to create a new character, whatever.
Ask Coyote 6 above, my Druid had Death Ward up very often, and it definitely saved me several times. I was prepared for such things, and as a result I lived, and this was in 3E too. It really helped me live through "Bloody Jacks Gold".
*sigh*
Wish I was still able to play with you guys, Coyote.