The "double taxed" theory has been debunked here -
http://thefinancebuff.com/401k-loan-double-taxation-myth.html
My company charge a flat $50 to process regardless of amount, not 3% - that is a lot if true.
I took out a 20k loan for my car when the DOW was at 13k - so the amount I withdraw was not hit with the downturn had I left it in my 401k when it went thru the roller coaster ride. The DOW was still at 11k when it was all paid off within 3 yrs so rough estimate, I escaped the 8% drop. On top of that I gained 3% paying back to myself. So instead of a loss, I gained 11% on the 20k I borrowed instead of paying 5% to the bank for a car loan. Is this voodoo math?