Contax legacy

I have been lurking this newsgroup for a while, getting a lot of useful
information. I now have a question.
I am one of the (many?) owners of contax/yahica systems who have been
left without a smooth path to digital photography.
I am just an hobbyst, and I don't have any of the more expensive Zeiss
lenses, but still I have a good range of stuff and I guess that some
could be occasionally useful even after getting a digital body (for
one, the normal 50/1,4 planar could turn out a nice portrait lens, or
my macro set could still be used).
So, thinking of getting a digital camera I thought that it could be
wise to look among those that could use my old lenses.

Searching around, it seems that adapters exist for using manual C/Y
lenses on Olympus and Canon.
If I understand correctly, to use them on any of those cameras, after
buying and mounting the adapter, one should first frame and focus
manually with the lens wide open, then meter manually closing the
diafragm at the desired F stop (without it being shown on the
viewfinder). Somethig to which one could be get accustomed, but clearly
limits the situations in which it can be done probably to still photos
of when using a wide angle lens with broad DOF.
What may change between different models is the usability of the
fiewfinderfor for manual focusing, since all of them are designed
primarily for autofocus.
So my questions a
All other considerations apart (sensor, noise, lenses, commercial
perspectives etc) which is the camera more easy to use in manual focus,
among Olympus E300 and E500 and Canon 350D?

Are there other issues about using C/Y on those cameras?

And should I bother at all?

thanks
Piersante