Could 10yr "Fixed ARM" be better than 30yr fixed?

[Michael Healy]

Hi everyone, 

I've been flipping for a couple years now and I'm working on making this recently rehabbed home into a rental. (BRRRR method of course) The bank is offering a 30 year fixed at the price I purchased the home ($125k) or they will offer more cash if I go with a 10 year fixed rate that becomes an ARM after ten years. That loan they will keep in house aka portfolio loan. The 10 year comes with a ONE percent lower interest rate (3.85% vs 4.85%) and lower closing costs.

Are there any pitfalls I need to be aware of?