No, Maybe...

Dear J,

Officially, Atlas says "Minimum 18" radii".
(They say it for a reason, and it's pretty unambiguous)

Unofficially, you've got (only) anecdotal evidence,
sourced from whichever modeller you happen to ask,
on track of unknown/indeterminate make/brand/type/installation quality,...

(Sure, there may be that one Modeller
who has spent decades perfectly optimising every element of their specific
   track-installation
+ loco tuning
+ car-selection
+ couplers

so that the resulting combination-of-factors "works without trouble" around a "nominal" 15" radii curve,

but are You willing/able/competent/experienced-enough to put in the same ammount of effort and diligence,
to confidently push-forward, and successfully replicate their results?)

FWIW, Personally, I wouldn't,
a shorter Switcher loco is the better bet for "without trouble" results...
(or, at least, stands a better chance of "bending the Min 18" radii R-o-T" than a longer/larger loco)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

PS for the kind of small/tight-radii switching layouts you've been contemplating,
"uncoupling" (sorry) the coupler-swing/overhang geometry issues from the "will it traverse the curve" question really is a non-starter... unless you fully-commit to never running around the Tight Curve with a car coupled to the loco...

WOW, that would look good!

WOW, that would look good!

Officially, Atlas says "Minimum 18" radii".

Probably best to stick to that and modify your curve radius. I once had a small layout with 15 in radius and it worked with short engines but I'd much prefer to step up to 18 in at minimum, just a lot more room for error there as far as coupler swing, engine truck flexibility, etc......DaveB

Also check the cars