If you were without a truck and buying, I would point you towards the 1/2 ton trucks for a better tow vehicle. If you are hitting 5500rpm with any regularity, you are pushing that truck to it's limits.
It makes no sense to rule out the ecoboost but include the small turbo diesels...The ecoboost has a longer track record (I was skeptical early on but so far the record has been good and the ecoboost line is expanding and I believe the most common engines being sold in F150s) and the diesels have those same expensive turbos.
But!!!!! Since your current truck is a 2019 and you are otherwise happy, $2300 is going to be far cheaper compared to the net cost after trade in buying a new truck. Now if you are considering a 2-3yr old truck, it might be close to a net $0 cost (if you sell your current truck private party).
