desktop keyboard: Logitech Internet 350 Keyboard
laptop keyboard:  Dell Vostro 3750
same OSes: debian wheezy x64
linux kernel: 3.2.0-1 (3.2.4-1 and 3.2.6-1)
tested synergy versions:
- 1.3.8-1 (debian package)
- 1.4.5-1 (debian package)
- 1.4.7 (own build)

/etc/default/keyboard:
XKBMODEL="pc105"
XKBLAYOUT="pl"
XKBVARIANT=""
XKBOPTIONS=""
BACKSPACE="guess"

same physical keyboard layout (regarding provided below keys):
qwerty with one row enter below \

desktop on desktop:
`1234567890-=
~!@#$%^&*()_+
qwertyuiop[]\
QWERTYUIOP{}|
asdfghjkl;'
ASDFGHJKL:"
zxcvbnm,./
ZXCVBNM<>?

laptop on desktop:
`1234567890-=
~!@#$%^&*()_+
qwertyuiop89-
QWERTYUIOP{}|
asdfghjkl;'
ASDFGHJKL:"
zxcvbnm,./
ZXCVBNM<>?

laptop on laptop:
`1234567890-=
~!@#$%^&*()_+
qwertyuiop[]\
QWERTYUIOP{}|
asdfghjkl;'
ASDFGHJKL:"
zxcvbnm,./
ZXCVBNM<>?

desktop on laptop:
`1234567890-=
~!@#$%^&*()_+
qwertyuiop89-
QWERTYUIOP{}|
asdfghjkl;'
ASDFGHJKL:"
zxcvbnm,./
ZXCVBNM<>?

problem 1:
Keys [ ] \ don't work properly for client (as it is shown above: 8 9 -),
yet they do work if Shift is used.

problem 2:
Polish letters don't work, giving only letters used beside Alt.
[ I no longer remember, but in 1.3.8 they possibly didn't appear at all. ]
They should work as folows:
Alt + e = ę
Alt + o = ó
Alt + a = ą
Alt + s = ś
Alt + l = ł
Alt + z = ż
Alt + x = ź
Alt + c = ć
Alt + n = ń
(and upper case versions with shift/capslock, of course)


UPDATE 2012.04.13
=================

I've asked about synergy alternatives at #debian@OFTC stating the problem,
and user 'saep' wrote:

23:19 < saep> przemoc, for me it works, when executing "setskbmap de" on the connecting machine

There is a typo here, because it should be 'setxkbmap'.
I've tested following command on the machine running synergyc:

    $ setxkbmap pl

And it really works!