However, seeing as though I have already sourced the deal myself, would it still be in my best interest to use a realtor for this transaction if it works out? 

An investor who has participated in a subject to transaction without lender approval should NOT assume that they are safe from note being accelerated because a certain amount of time has passed.  

An agent told me that 9/10 transactions they handle are cash and not financed - so i think in this particular submarket going in with financing really weakens you.  

This would be a prohibited transaction since you're a disqualified party and anything you already own (your LLCs) is part of that. 

In effect, you will end up paying tax on your refi cash later on, when you sell the property.

There are far too many regulations, the transaction is a much longer process, and we are talking about someone's biggest purchase.

As a rental strategy for non owner occupants, it absolutely is a fantastic way to generate the highest return, that's true.....but also, and most importantly, your screening has to be on point, and without that, it won't be as effective because one bad roommate can ruin the environment for the other roommate tenants. 

Additionally, working in a small-town market taught us how to effectively price properties for faster sales without compromising profit.

With an LLC, you may be able to deduct business expenses more effectively and avoid double taxation.

They can bring it to open market and facilitate the transaction.