Personally, I'm liking what I see in the new Defender... my biggest gripe (as it is entirely untested by the public at this point), would be the lack of diesel offering in the US market... and yes, given the published GCW/tow capacity ratings, that diesel needs to be more in the neighborhood of 450 lb ft of torque.
My last 5 vehicles have all been diesel, perhaps I'm biased but justifiably so IMHO. While I agree small displacement turbos and mild hybrids are beginning to blur the lines between diesel and gas, there is still no substitute for a diesel in terms of low end power and range/mpg. To make my point, I did a bit of digging. Since the EcoBoost was mentioned as an example of a [superior to diesel] small displacement turbo, I dug into the Ford EB vs baby (3.0?) Powerstroke to do my best to compare apples to apples... The difference is significant - dyno tested stock at the rear wheel: 280 lb ft @ 2000 rpm for the diesel vs 200 lb ft @ 2000 rpm for the ecoboost. As far as mpg across the two: the baby diesel bests the ecoboost by 100 (towing) -170+ miles of range... that's the difference between needing to fill up every 200 miles vs every 300 miles when significantly loading the engine. Significant and important to me and how I use my vehicles.
My real world example of the benefits of low end power... towing my buddies old Shasta camper into Kane Creek trail (Moab area), with two dirt bikes in the bed of my Cummins 2500 and having a hidden campsite all to ourselves right off the trail. After climbing back out of there while hauling a trailer, crawling over rocks on a steep incline with zero tire slip, my buddy who is a diehard Toyota guy, said, "no way we coulda done that in my Tacoma." (granted that's not a small displacement turbo gasser)
Fast forward about 5 years and I no longer need to haul boats and horses, I'm in an EcoDiesel WK2, sufficient to haul my 12' enclosed trailer with 2 motorcycles and gear around the Rockies... Same buddy, always giving me crap that it's a soccer mom car is jealous I'm getting 13mpg towing with 275/55R20 AT's (the biggest that will fit my WK2 w/o mods). My buddy remarked he's lucky to get that driving Telluride to Denver w/o a trailer in his latest model TRD Pro Tacoma with aftermarket tires and ARB bumper... Meanwhile, I'm still driving down "Jeep" trails and finding campsites like this one from last month...
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Outside of regular maintenance (oil change, fuel filter change, brake pads, etc.), I've had zero reliability issues with my past 4 Cummins and my current EcoDiesel - but yes, modern EPA/CARB stuff has complicated matters. I went from a 2004.5 Cummins to a new 2010 Cummins and then back to a used 2006 Cummins because of the ULSD/DEF stuff absolutely killed the mpg (about 17 mpg empty highway on the 2010 back to 22 mpg empty on the 2006). And now with the EcoDiesel and the "Approved Emissions Modification" I've noticed my mpg suffer yet again. Of course there are always examples of this one or that one failing - doesn't mean they are all unreliable. I towed my buddies wakeboard boat to the lake last weekend (comfortably at 70 mph when conditions permitted), because... His F150 EcoBoost had been at the dealership for 2 weeks.
And if diesels are (should/will be) going the way of the dodo bird, then why is the entire domestic 1/2 ton truck segment, many SUV's and Jeep (hopefully) offering them now/recently? It's a good thing to have options and no two overlanders are alike.
Back to the Defender - there's the old vs new argument, but time hasn't stood still for me. I drove to Alaska when I was 20 in a 1974 VW bus; took the Cassiar Highway (that was long before it was paved) and we survived (minus a broken rear shock we had to wait a week for in Whitehorse), and up to Manly Hot Springs where I had to change a tire. Today, I can afford a $70-80k car, and because of that I also appreciate and like to have AC seats and IFS with air suspension. If I were to drive to AK again I'd happily do it in a new Defender, but I'd have to go out of my way to find some roads the Defender couldn't handle and in the meantime I'll lower the suspension to save some fuel and be comfortable.