What is the brand of the pleated filters you are using? My opinion is STANDARD pleated filters are the way to go if your ductwork can handle them. By standard I mean not ultra-restrictive, like the 3M Filtrete filters. Just make sure you check/change the filter once a month. I use Flanders NatureAire standard pleated filters (I buy them from ushomefilter.com) and wouldn't use anything else after the way they've worked for me. Good filtration with not too much restriction. Not all systems have proper ductwork for more than a standard fiberglass filter, but I'm willing to guess that you'd be fine with them. Maybe you can take the filter out for a short period to see if the blower ramps up a lot when you put it back (and it likely will, but you can see if it does noticeably); that way you can see if it is too restrictive. Personally I think you're fine with standard pleated filters, but I need to know what kind you're using.

I answered your question on HVAC-Talk.

A MERV 8 pleated filter is not too retrictive. The cheap-o spun blue fiberglass filters allow too much dirt to deposit on your evap coil.

I use the Natural Aire standard pleated filters, MERV 8, from HD for my new heat pump air handler.

Change the MERV 8 filters monthly and you should be good to go. They're only $7 for a 3-pack so it's cheap to change them out monthly and keep your coil clean at the same time.

Good luck.

I'm the same way as Gary but pay more online since Lennox uses a seemingly uncommon filter size in my particular air handler, 18x25x1--I cannot locate any at HD.

When was the last time your Check Engine Light came on for your heat pump?

A decent pleated paper filter, changed regularly, will serve you better and the local techs worse.