Carrier 18VS or Trane XV19?

Narrowed down my heat pump replacement to two quotes and I'm feeling lost at which way to go. Would greatly appreciate any insight you'd be willing to share. We had some extremely high electrical bills last winter because of a failing heat pump, so efficiency and quietness are core priorities. We want to stick with the higher end variable-speed units. The Carrier has me really intrigued because it will operate down as low as 25%, while the Trane can only operate as low as 50%. However, the Trane is quieter (43-57dB), while the Carrier is 55+ dB. I have to assume the Carrier operates in a 55-75ish dB range since I couldn't find the upper limit published. The Carrier is also only 5-stage "variable" vs. 500 variable stages on the Trane.

I think I'm leaning Carrier because the installer is way more responsive, the fact that it has the lower limit of 25% capacity and is cheaper. They both seem like great units, and on the Trane's side they seem to be insanely quiet with the side-discharge units. I also like the smaller footprint of the Trane, but it's not necessary in our situation. I also like that the Trane is fully variable, but I don't know if that's completely necessary. Carrier's 5 stages sounds like it should be plenty, especially if it ramps down all the way to 25%. Both units are effectively 19 SEER/11 HSPF.

Is this sound reasoning? Should I be looking at the larger Carrier Infinity 24 Greenspeed? The HVAC installer said the 24 would be better for cooling (not a concern in the Pacific Northwest) and that heating would be about the same between the 18VS and 24. In his opinion, the price increase to the 24 wasn't worth it for our situation.

Trane XV19
Model Numbers: 4TWL9036A + TAM9A0C36 + TZ0N1050

Pro's:

• Side discharge
• Quieter (43-57 dB)
• Fully variable (500 stages)
• 5-year labor warranty

Con's:

• Variable speed only goes down to 50% capacity minimum
• Company installing has been difficult to nail down on availability and responsiveness - have pause for concern.

Carrier 18VS
Model Numbers: 25VNA836 + FE4ANF003 + SYSTXCCITC01-B

Pro's:

• Variable speed operates as low as 25% capacity
• Install company has an excellent reputation and have been very responsive.
• Cheaper (by $1600 - saving money is always nice, but I'd rather get this right and not regret my decision down the road when spending good money overall on a new system.)

Con's:

• Variable - but only has 5 stages, not "fully variable"
• 55dB is minimum (assuming it goes up to mid-70's dB). Louder than the Trane
• 1-year labor warranty

source https://hvac-talk.com/vbb/threads/2242748-Carrier-18VS-or-Trane-XV19?goto=newpost