Repair or replace

I have a 18 year old home in Maine with an oil fired furnace and a power vent. The power vent is the original and is getting loud. Do I spend money to replace vent or do
I look for a more efficient furnace? The furnace is very dependable, which is important to us as we decamp to Florida for 6 months in the winter. I have read about direct vent oil furnace, we do currently have a tankless hot water system. Propane for the last 24 months is more expensive than oil.

Thanks in advance for any thoughts