I believe Chicago has too much industry to "fail" or crumble however  people who actively assess different markets in terms of cost of living, taxation, infrastructure,crime etc are finding better suited opportunities for themselves in other states.

Then, shareholders are taxed on whatever income they receive from the C-corp.Do a quick google search on "C-corp double taxation".In an S-corp or LLC, the company is not taxed on its income. 

Investing in notes generates interest income which is not offered any preferential tax rates.If you decide to invest in notes personally - you may subject you to state taxation in the state that you invest in and an additional state tax return.Let me know if you have any other questions.

I’m a CPA, and have experience with rental properties and multi-state taxation.

In my opinion - there are other areas that will generate a better rate of return.In regards to the taxation portion. it depends on what your basis is in the property.considering the property is now a rental property - you are depreciating the property and the basis of the property every year.So when you sell the property you dont take selling price minus purchase price = gain.

However, if you truly develop and sell or build and sell you'll pay tax at that point. 

The advantages of the Solo 401(k) are:Higher contribution limits than IRA based plansAbility to make contributions of up to $24K on a Roth basis, without limits based on incomeAbility to personally borrow from the plan up to $50K for 5 yearsExemption from UDFI taxation on mortgaged real estate investmentsStronger protections against creditors in cases of personal lawsuits or bankruptcyLess catastrophic penalties in the event of a prohibited transactionThe advantage of a self-directed IRA is a certain simplicity and permanency with no need to maintain ongoing self-employment.

I know of a few good accountants that specialize in real estate investors, business owners, flow through entities and the taxation that follows them which is what REI's typically utilize.To determine what's best for you we'd need to know the scope of work that is involved with your specific situation to see what level of tax professional is best suited to serve you.IE we dont want a person who needs a min 1040 cost of 350 to be paying a tax professional who charges a min 1250 on a 1040 filing as it would not be cost effective for that person.Hope that helps.

So nothing to do with the taxation of the real estate.But that is just my understanding

You may not personally benefit from the IRA income (other than growing your retirement savings) nor may you add value to the IRA through the provision of goods or services.An IRA would be subject to UDFI taxation if it used debt-financing.If the IRA is flipping properties on a regular or repeated basis, then it is acting like a business and subject to UBIT taxation.