Hello, I am looking into refinancing my owner occupied duplex to getting rid of my PMI and take advantage of lower interest rates.

Each has its own advantages and disadvantages.Syndications typically require an investor to be accredited, which if you are saving 9k/mo, you might be very close to, if not accredited. 

I would love to take early advantage of that new lake as well.

That's a BIG advantage depending on your plan for the property. 

I assume your client is looking to take advantage of PR's Act 20 and/or Act 22.

On Residential Conventional there are advantages that you should know of, which are:- takes into account your other personal income sources to qualify and why this is so huge is that the property doesnt need to necessarily cashflow in a way that a commercial DCR model would require. - your max loan sizing can up to 70-75% of your appraisal on investment cashout and is NOT limited by cashflow however the cashflow you do file or can document with your lease agreements or taxes will help offset and help you qualify for the cashout as well- cash out is 6 months title seasoning through your name personally or through entities you controlled a majority stake in (51% or over)The down side on residential conventional financing is that you can only finance the properties in your personal name at closing or your living trust. 

The advantages for a line are that you can go to a higher loan to value, around 90% in most cases and in some rare instances up to 95% of your homes appraisal figure.

I know there are advantages to an LLC but not sure what the primary advantages are.  

While every investment possesses its inherent risks, I believe the article fails to address the many advantages of owning real estate, including mortgage interest deductions, possible income off-sets resulting from depreciation, and accelerated growth potential when employing leverage. 

If you have a better strategy or a competitive advantage, you can find/make great deals through brokers.