My next big decision is whether to pay off the mortgage aggressively and move the house into an LLC or corp for financial protection, or if I will go with an umbrella insurance policy and continue to invest in new properties.

@Jami MortonWhen I read your post above, It sounds - please correct me if I am wrong - as if you have a pile of IRA money and are out investing without much education.There is much more to navigating the tax code related to using a self directed IRA than "can't be for personal use".I hope your custodian or advisor provided you with some introductory guidance as to the rules for self directed IRA plans and/or that you have a good CPA or attorney guiding you.Flipping with a self directed IRA can be very profitable, but is an advanced strategy.All IRA transactions must be entirely at arm's length, meaning you can negotiate and make decisions, sign contracts, and handle expense and income transactions, but may not benefit in any way OR add benefit to the IRA through the provision of goods or services.  

Cash flow is my end goal, but in order to reach that point where I can afford those kind of properties I'm left with the method mentioned above unless someone can give me any better ideas.Please, anyone reading along this thread; would you please give me some pointers if my mindset is not in the right place or there is a more optimal route I can take.Ideally, I'd like to keep my potential business partner because of the fact that he would cover any labor costs in the present as well as in the future and is giving me full control of the property in terms of tenants, decisions on holding / selling, and what to do to properties in order to appreciate their values.

There could be strong logic so it might be the right decision.

It comes down to your investment horizon.Good luck with your decision. 

The more familiar you get with the numbers the more solidified you should be in your decision making when that time comes.  

A bad financial decision can set us back a decade.

Ideally someone who's defended their decisions in front of the IRS and won.

The interest you are paying on the loan is paid back to your own retirement account so you are in essence helping it grow and if your money were sitting in a money market earning 0.5% it would make sense to take the loan out and pay interest to your own retirement account instead of some creditor and this would also mean that your 401k is getting guaranteed 4% interest.All of the above and more need to be taken into account in order to decide if this would be sound financial decision. 

Don't offer to mediate, don't offer to make a decision in "favor" of one or the other.