lol yeah your problem is pretty common for the PNW. I'm up in Seattle and did the same swap a couple years back. The issue is that most heat pumps start losing efficiency hard below freezing, and Portland gets those random 25 degree spells that kill your savings. You gotta check if your unit has a cold climate rating or if it's one of those cheaper ones that's really only meant for mild winters. If you're paying 75 bucks extra in a bad month, that's honestly not terrible for a non-cold climate system. The real game changer is making sure your heat strips aren't kicking on too much, some people's thermostats are set to switch to aux heat way too early and that's what eats your wallet.

Wait, have you noticed that same thing shows up in all kinds of work? I feel like there's this big pattern where what we think is "wasting time" or "overkill" actually saves us headaches later. In my experience, taking an extra few seconds or using a few more screws almost always pays off. Like, I used to hate spending time cleaning my tools after every job, but then I started doing it and my saw blades last twice as long. Your mileage may vary of course, but I've seen it with drywall, with woodworking, even with just fixing stuff around my own house. The shortcuts we take to save a few minutes often cost us hours down the road.