Anybody ever use these
 

And if so what was the benefit

https://www.moog-suspension-parts.com/moog-k5250

Although I have never used them, the benefit is allow more adjustment for alignment. Older frames have a tendency to twist over many miles not giving you enough latitude to get the alignment within specs. The offset shaft moves the pivot center on the upper A frame without having to resort to pulling the frame to get it back to the original factory specs.

That's what I was told when I brought my old Firebird to the alignment shop.

Used these effectively on my 1968 Firebird.

Did you notice a difference? Did it come with improved alignment specs?

It's been a while since I did this. I had been told that my frame had sagged and that made it difficult to shim for alignment properly. I got my specs from http://www.pozziracing.com/first_gen...gnment%20specs

I think I'm running -1.3 Camber, +4 Caster and 1/8 toe in

See if you can get the alignment you want with stock shafts. If not, then get the offsets

They are called "Problem Solvers". Here's the quote right off the link you provided.

Front Control Arm Shaft - Chevrolet Camaro
Fits Left or Right Side. Offset Shaft Kit Provides Additional Camber Adjustment of up to 1-1/2 degrees

Yeah, I used them on two of my cars, and they are great.