sell rental in higher cost area to buy multi-families in lower?

[Maria D'Aura]

I've been searching the mls in lower priced areas within 2 hours drive of where I live. In analyzing them it seems we would have a (much) better monthly cash flow if we sold our SF in a higher cost area and bought 2-3 multi-family properties in a lower cost area. 

The numbers look like: $4,000/mo vs. $1500/mo. cash flow. 

Has anyone done this? Risky when the SF is performing well with very few issues and tenant turnover? Or would you refinance to pull money out and buy the lower cost multi-family? Of course this would change our monthly cash flow on that property.

What other things should I consider?