Ford was sorta using hp in their trim differences around 2019. For example my Platinum Expedition was listed at 400hp, the lower trims were sub 400 in the marketing papers. The Lincoln version was 450 etc. I noticed all the trims were pretty much 400 by 2023. 91 definitely changes the tune pretty noticeable difference between 87 and 91 regarding performance.
If you go find the tear down videos of the recent versions of the 2.7 and the 3.5 they are super beefy with some block structural features you don’t see in other engines. Definitely built for truck applications.
The 3.0 is quite different built for lighter work loads but higher RPM performance basically the race car engine version of the 2.7.
The 2.3 is heavily updated since its early days also.
My understanding about all the cylinder deactivation the primary issue is the valve actuator thats part of the deactivation mechanism starts to fail and causes valve failure GM and Chysler both apparently are well known for this issue by the engine builders. GM LS those guys convert them back to standard valving to avoid that failure issue. Not sure about the Fords I kinda suspect Ford shied away from it due to those issues and finding fuel economy saving in weight loss and more gears.
There are two 3.5's: The regular one and the HO. The major differences are the HO has slightly lower compression, larger turbos, and more aggressive tuning.
As for octane, the truck has a very accurate knock sensor and monitors knock closely, and adjust the timing and fuel curves accordingly. There is something like a 20-25 hp difference between regular and premium fuel on an otherwise stock EcoBoost. Much to the dismay of raptor and Limited owners, for about 600.00 you can easily tune a regular 3.5 to make more power than the 3.5HO.
I ran a set of CR stage 3 cores in my stock turbo housings on my 2015 and had meth injection. It was probably close to 475-500Hp at the rear wheels. It held up well for the 240k that I had it. It could spin all 4-35x10.5s on dry pavement without much effort.
The 3.5 EcoBoost is based on the old NA 3.5. The 2.7 was designed from the ground up to be a twin turbo, full size truck engine, so it’s internals are very stout. I almost went with the 2.7, but they were brand new when I bought my F150 and the 3.5 was a little more proven.