David Nebenzahl wrote:
Myself, I really don't see the point.

I interested in single-tray because,

1, My room is not large, even thougth it's capable use three trays,
use one tray only is attractive to me;

Well, that seems like the only compelling reason to use just one tray
(although the "tray ladder" suggested here might be a workaround).

2, Using one-tray method means I need to pour solutions back into its
container, this is easy to maintain solution temperature in a water
bath;

But that's what makes this method much more a pain in the ass, in my
view; all that pouring in and out of bottles. And in black & white
processing, who cares about "maintaining solution temperature"? (You
aren't processing color paper, are you?)

3, A well built, larger, dedicated photographic tray is not cheap.

Really? At least here (the US), trays are probably the cheapest items in
a darkroom. Where are you?

This may very well be true for small sizes (up to 20x25...).

For larger sizes the single tray method is excellent. I use a Durst Printo
for all proofs and test enlargements (with RC paper of course) and make the
larger baryta prints using a single tray (up to 100x70cm...)

Martin