The only real point I agree with is that the Toyota diesels will fit into some of their platforms easier. A 1KZ-TE may fit into a 4runner with relatively little drama, I don't know if the same would hold true for swapping it into a Tacoma. Moreover, any swap would require some reprogramming of the ECU, which would add cost and complexity to that operation.
The half cuts and drivetrain pulls come with an ECU. That why when you buy your JDM pull you have to specify automatic or manual to get the right ECU. The engines in 4Runners and 2nd gen Tacomas are the same, I dunno. It's not like a US-spec 4Runner has two sets of motor mounts, so whatever changes it takes to replace a 1GR will have to happen either way. It's not a like our 4Runner is going to have the same harness that a GX spec Prado with a 1KZ, 5 speed stick, steel wheels and a vinyl floor had anyway. A Tacoma was available with 2TR-FE and R-series manuals that are typical globally, so who knows, it may just plug right in.
There is a potential savings by getting a used Toyota diesel. The caveat you refer to is an important one though. The 2.8l Cummins is brand new and comes with a warranty; the Toyota is a used engine with no warranty. Granted, those overseas diesels are known for being fairly trouble-free, but still that comparison is not apples-to-apples.
The Cummins crate engine comes with a 2 year/2,600 hour warranty that starts upon delivery to the first owner. That's something the Dieseltoys FAQ mentioned (although they were wrong about 90 days). If you buy one and it takes 6 months to get your swap done you only have 18 months more warranty. BTW, I was wrong, the R2.8 Repower kit is $8,999, not $10k.
It's also true that you'll probably get a somewhere around a 30 to 180 day warranty on a used engine. If it hasn't been overheated that should be fine. It is certainly a risk, but then again you're replacing a used engine in your truck so it's not like used should mean abused or tired.
Also, they usually source them from Japan where I surmise they require a very detailed inspection (
Shaken) that results in very few vehicles getting more than 50,000 miles on them. Just a bit of body damage or illegal modifications are grounds for failing a car. The vehicles are apparently not beaten up and kept in very good repair as a result, so the JDM engines usually are in very good condition.
Parts availability and repair I think you're being a bit unrealistic on. Toyota in Canada and Mexico may carry some of those parts, but they're less common and more expensive than the parts you're normally getting from a Toyota dealership. Moreover, it's highly unlikely that most of the Toyota dealerships are actually trained to handle those kinds of engines. I think the logistical coverage for the 2.8l Cummins within North America is much better by comparison, and it will continue to improve if the 2.8l sees usage in future midsized platforms (like the Nissan Frontier).
I didn't say they would be
stocked, the EPC has all the part numbers so
any dealer anywhere in North America can
order the parts and they'll be delivered from a warehouse in North America because they support retail and commercial buyers in Mexico and Canada. Some dealers (like American Toyota in Albuquerque) have TLCA affiliated parts guys who do manage to stock common parts for the enthusiasts, though. My point is you don't have to have a special English speaking source in Japan shipping stuff to you.