I recently got a large commercial property under contract and was told by my lender that my experience/portfolio was a factor in getting approved. 

I know it depends on many factors and I am asking you to make a very broad generalization, but in general would you think that it would be likely to get similar cash flow or CoC return in a syndication vs being able to leverage up with conventional financing in rental properties.As for HML, I have invested a fairly small sum to get a feel for it. 

Does either currently have a PM company, or would you need to find one (a major factor in an out of state investment).

There are a number of factors to consider; how long your brother has owned it, value of the property, type of building and specialty options (charging stations for electric equipment, etc.), fencing and security systems, and numerous other factors. 

Whether they are on a long-term lease or on a MTM rental agreement will also factor in.

In addition, your DTI ratio will certainly be a factor at some point in your investing.

So, if our our borrower has a large arrears balance, when we do a loan mod we may factor their new rate and term on the actual UPB and defer the arrearages as a deferred balance due at the end of the term.

You factor for the appropriate amount of maintenance that is likely given the condition of the house and if the numbers still make sense you're good to go!

Carpet and paint, rent forever kind of thing.

Figure out your PITI then put in factors for vacancy, repairs, and property management, if you intend to use it.