Mercury-free vs mercury switches (vaporstat/t-stat/pressuretrol)

scottie_2

Dear All,
I have read some on the wall about mercury-free vaporstats. Are they as reliable as the old mercury ones? I am looking into upgrading my pressuretrol. I would hate to spend the big $ on a non-mercury model that is less reliable than the older mercury models. I have done some searching and found the older mercury models are still available brand new. How do you guys feel about the performance of the non-mercury ones? Do you still prefer the mercury ones?
Also, should I keep my mercury honeywell round t-stat or upgrade to the new mercury-free version?
Thanks for looking