Please help me Evaluate this Refi Offer

[Alan Ford]

Hi All - I will keep this facts only with bullet points:

1. Currently on a 30 year fixed at 3.5% that began June 2016 - I owe 546K and change.
2. New Loan is at 510,400 (Confirming limit for county) - 30 year fixed rate of 2.5%.
3. I have to pay $36K towards the principal to get it down to the $510K loan limit.
4. In addition - I have to pay an addition 10K in total loan costs - points and closing costs.
5. I would pay the 46K or so needed to close out of my HELOC - the rate on that is prime and a quarter point. Currently 3.99. I should be able to pay off this 46k out of the HELOC in roughly 1.5 to 2.5 years.
6. The monthly PITA goes down a little over $600 if i refinance.
7. I don't intend to sell the property - i would like to rent it out in a few years after i move out of it.
8. I like the idea of a lower payment because it helps with future DTI calculations if I expand my real estate portfolio.
9. I dont know if using money out of the HELOC to pay down principal in order to secure the lower rate is worth it.

Could really use some guidance here folks. Thank you!!