They dont know the correct answer half the time either.....~:

Get three estimates on a new system at the very least...get the
estimates from people recomended by friends family neighbors.

8 years....its a toss up.... I would probably go ahead and get a new
system....your present system could last another 5 years but once some
slackjaw hvac "technician"...and I use that term loosely... starts
messing around with the refrigeration end of the system he opens up the
door to moisture and contamination problems in the equipment.

No matter how many good recomendations you get on an hvac dealer or any
other tradesperson you have at best a 50/50 chance of getting the job
done right or getting completely hosed.

Get a new system...get the 10 year warranty....you will be set.