Todd H. writes:

the R410A units were a lot more reliable and had
longer warranties because they cooperate with lubricants a lot
better than R-22.

R-410a must be run at much higher pressures than R-22, so it tends to be
*less* reliable. The "cooperate" and "longer warranties" stories are
the big-lie approach, kind of like selling a lawn mower as being
"quiet".

HVAC dealers tend to be like bankers selling mortgages. Somehow you
will be saving money by giving them all the money you have.

Be suspicious of any efficiency claims that justify tearing out a
working system. Ask them if they'll guarantee your electric bills will
go down that much, as opposed to just hand-waving.

You know, the energy crisis was in the 1970s. In the late 1970s and
then the 1980s and after everybody bought efficient systems. The
efficiency "improvements" since then have much to do with tricked-up
measurement schemes. Be suspicious of anyone who asserts your old
system was inefficient cuz nobody cared about efficiency back when it
was installed, or that everything in the 80s or 90s was inefficient.

This dealer's Web site has a good analysis of the R-410a claims:

http://www.garnerac.com/r410a.html