But what about the interest on a cash out refinance?

What you describe sounds a little like a BRRRR (Buy Rehab Rent Refinance Repeat). 

But be careful expecting to refinance.

By the time I reach 20% equity (likely 3+ years away), my monthly mortgage payment will come down when I refinance, but $600 is a big hit to the numbers. 

I'm hesitant to give up my conventional loans on the next cash out refinance for DSCR loans.

I'd keep the rental and by no means refinance it to take cash out. 

Refinances are still active, slim pickings but some players are out there who are direct lenders, flip loans are also available (75-100K) min property other than conventional and gov backed loans.  

Would a cash-out refinance to free up equity and keep growing be a smart move, or should I focus on paying down my existing debts?

I currently own a two-family home with my girlfriend, but I plan to refinance in 2025 and start fresh with a focused expansion strategy.

we need our own forum for this concept. I'd argue that there are very select zip codes where this strategy works. You need to find a zip code where land values are 10% of less of after built value. You have to find a ...