I have that G-force axle from Rocky Mountain. The only advantage that it has over spacers is looks. The chrome finish is nice for the first few rides. After that. It starts to look beat.

It does have adjustable widths, if that's worth anything to you.

Also, I am contantly torqing the axle nut. I don't know if it is coming loose or what. But the axle gets sloppy after a few rides.

If you want to go cheap, just get the spacers. You won't feel a difference in the handling. Strength is not an issue.