Neck crimp vs. tension....

The topic for discussion at my local range was Lee factory crimp dies & the accuracy they improve on. Has anyone tried a comparison using a lee factory crimp die vs. straight neck tension?

On a lighter note, Santa (my loving wife) brought me a Lee neck sizing collet die set. It comes with a collet neck sizing die, a much better bullet seating die than what I have in my other die set and a standard FL sizing die. I'll be trying out some .270 / 130gr ammo I put together later today as soon as I can sneak away from the office. It sure does make life simpler & easier just sizing the neck, clean 'em up a little and reload 'em.
Can't wait to try the new reloads out.
Would it be a reasonable assumption that I may have to adjust the powder charge by changing from FL sizing to neck only sizing?

I doubt that you would notice much difference in powder charge from full length to neck sized. If you chronoed before and and chronoed after neck sizing to see any difference, that would tell you, and also if it shot to the same poi and are as or more accurate would tell the story. I love the Lee collet die, but much prefer Forster seaters. I don't own a 280, but that is a dandy cartridge. my 2cents.