I haven't heard of heat pumps going out sooner than AC systems. I would definitely go with the variable speed fan and two stage compressor. If the compressor is only single stage then you are usually the full power of the compressor on all days while the compressor is designed for the hottest day. Two stage just makes sense, less power usage when the demand is lower. Variable speed fans that are properly sized using Manual D to overcome static pressure loss will work just as fine as those constant speed fans in air delivery. You get the added perk of allowing the fan run at lesser speeds and therefore use lessor energy.
Originally Posted by AZag
Hybrid systems also allow you to adjust between gas and heat pump, so you get the biggest bang for your buck. If natural gas is cheap (as in right now), use more natural gas... in the future if electricity is cheaper... use electricity. The system is adjustable.
Like any system I would make sure you are getting that load calculation and duct pressure loss analysis. Also, if you want to control humidity, you also need a thermostat that can handle that too.