I'm looking for either a 235 or 260 MT7 for regional trips for my family of 4. (Two small kids, though growing like weeds.)

I keep going back and forth between these two models and was recently contacted about a nice 260. It's the useful load vs performance that has my overthinking brain spinning. Our mission would be to fly to our mountain cabin, go on the occasional camping trip and fly approx 500 nm to visit grandparents every once in awhile. My brother and I would occasionally trade out his Mooney when I need to get somewhere fast.

Would love to hear some expert opinions debate this one for me!

I'd prefer to fly an injected engine - that being said, a carb is more practical if you are getting off the beaten path. Options of mogas and hand propping come to mind.

The difference between the MT7-235 and MT7-260 sitting on the ground with same equipment is aprox 12 lbs in engine weight.
They two engines are both Lyc injected (pressure carb actually).
The 260 has a tad higher rpm of 2700 versus 2400 for the 235 and of course different comp ratio.
Both are same tbo.
If run at same horsepower production and given same prop thrust, fuel use is the same but if both run at same percent of power eg 65%, 260 will of course have higher gph use.
However the 260 can cruise a little faster but will then burn more fuel per hour.
The 260 has a performance advantage at altitude which can be noted after about 3000msl.
The MXT7-180 has a higher useful load because engine is 100lb apx lighter, but gives up cruise speed and climb and short takeoff performance to 235 and 260.

In actual use, the different Maule models are flown in a similar way.

I just bought a Maule M-T-7-235 (got it Saturday!!!!) While doing my research and before deciding on the 235 I wanted to see what the real world, real flight numbers were on the 235s and 260s.

I went to flightaware.com & pulled up all the "M7" models flying at that time. Flightaware lists all M7 models as 260's but by looking up the N numbers on aviationDB.com you can tell who is flying what model plane. A fair number are 180s but I did not pay attention to them. You can also look at past flights from the planes currently flying, so in an hour or so you can look at the flight profiles of multiple planes that flew dozens of completed flights.

Summary points, no statistical significance to this whatsoever & just my impressions:

-- During the early part of the day many if not most of the flights are low altitude short meandering trips, frequently back to the original airport. Fun flights, pattern work, IFR currency, etc.

-- Later in the day, there are more longer flights in progress.

-- There are very few night flights at all, but those flights seem to have the most speed.

-- On the longer day flights, many of them are at surprisingly low altitudes.

-- On the longer flights, both the 235s and the 260s seem to have groundspeeds in the 125 -135 MPH range. There's not a lot of difference between them as the planes are actually being used. At least I didn't see anything.

-- I was concerned about range issues in the 260s since the tanks are almost the same and I just wasn't seeing a big speed advantage with the 260.

-- I was concerned about the eventual overhaul cost of a 260 vs. a 235 if there was no apparent advantage to the 260.

I'm planning a long trip from Knoxville to Bozeman in June and I don't really know what to put into Foreflight for the 235's fuel consumption and actual speed for 65% and 75%. I would appreciate hearing what numbers other people are using.

I run my M7-235A at about 11.5 gph sometimes if pushing along, at 12.5, however I can also run it happily at 9.5 if lounging along for the sights. It all depends where i set the power. 45% gets most time in the air, 55% gets most distance thus best mpg, 63% and you can't over lean, 75% is best power at around 7500msl dependent on temp etc.
When i have owned 260s I go a tad faster but burn exponentially more fuel because of increased drag with extra speed. I have the choice of going at 235 speed and burning similar fuel amounts.
The MT7-260 this last week was flown to Mexico and back from Northern CA and mostly at 10500 mil and 10.5gph reported.
The trigears are a bit slower than equivalent taildragger because of nose gear drag, unless of course the taildragger has large tyres.

There isn't much cruise speed difference or weight difference between the 235 and 260. The difference is in high density altitude climb performance with a heavy load. If you are going to fly out of high density altitude airstrips with a full airplane, then the 260 might be a better choice. Otherwise, there's no real advantage to the 260 but there's definitely a purchase cost disadvantage. The scarcity of the 260s makes them more expensive.

More important than the 235 vs. 260 hp might be the condition of the airplane and equipment.

MT-7-235 Plan (no wind):
11.8-12 gph and 118 kts set at 2250 rpm and 21” mp.
Leaned to 75 rich of peak or there about.

There is no substitute for horsepower. And that 2700 rpm sure does sound fine.