ROBS - anyone have any experience (vs.self-directed IRA)

[Jill Green]

I am interested in starting a flipping business with a friend.  This friend is already a successful flipper, but needs more capital (so we can buy at auctions, etc., for cash).

I lost my job of 28 years, and have a 401k with my previous employer. I'm interested in reinvesting my 401k by using some of it to start a ROBS, or a solo-IRA.

Interested in advice on doing this, and which avenue I should go with (ROBS/IRA), what are the benefits/disadvantages of each.