426 stroker, is it reliable?

yep and 3.75 b wedge and 4.150 rb as for the 426 small block the arm is too long, reliability will be an issue.
John Deere builds tractors. lol

Please explain your reasoning.

There are tons of 4" motors out there that have been beat on for years with no issues. Also a bunch of 4.125" and 4.25" crank engines.

Can any of the nay sayers point out a failure that was proven to be stroke related?

I have no problems with short strokes, I loved my 340. But my 408 thought it was a big block and the 434 is a bear.