Using versioned self-obsoletes would be a convenient way to avoid Epoch bumps 
in a lot of cases.  However, they don't work (tested on FC-4, I don't have a 
more recent system to test with).  Reproducer specfiles attached. 
 
# rpm -qp --provides test-1.0-1.i386.rpm 
test = 1.0-1 
# rpm -qp --provides test-1.1-1.i386.rpm 
test = 1.1-1 
# rpm -qp --obsoletes test-1.0-1.i386.rpm 
test = 1.1 
# rpm -qp --obsoletes test-1.1-1.i386.rpm 
(none) 
# rpm -i test-1.0-1.i386.rpm 
# rpm -U test-1.1-1.i386.rpm 
# rpm -q test 
test-1.1-1 
# rpm -U test-1.0-1.i386.rpm 
        package test-1.1-1 (which is newer than test-1.0-1) is already 
 
I would expect 1.1 not to be treated as an upgrade over 1.0, but yes the other 
way around.