Heloc vs Mortgage in this situation

[Thomas P.]

I've read and read on the HELOC topic of paying things off faster than a mortgage using a HELOC, but I'm not sure I've got my answer so I'm going to pose the scenario to the BP community:

Let's say we owe $57,000 on an LLC owned rental. It's on a 5 year balloon, 25 year amt at 5%. Payments are $514/month. Year five is coming up May 2017 and we will have to refi. My question is, if I paid the house off and took out a HELOC for the payoff amount to cash out (assuming I can find a bank willing to do a HELOC on a rental property), it looks as though I could pay the house/HELOC off faster, around 10 years, if I just kept making just above same payment I am making now of $543/month. This is a assuming a HELOC of 10 years fixed at 3.5%. This versus getting another 5 year balloon, 25 years amt at 5% and having to pay the refi costs.

Is my math wrong?  Even if it's not, is their a better vehicle with a better combination of cashflow/paydown?