Using equity from primary residence to put down payment on multi-family investment

[Johnny Kula]

My broker mentioned seeing I have cash to put down on an investment property, rather than using the cash, use the line of credit on the equity and put the savings in a "safe" investment fund or somewhere that I could liquidate and pay down line of credit if rates start to jump, etc. 

Is this something recommended?  Anyone have any thoughts on why/why not this would be a good or bad idea (besides the obvious "don't spend the cash").

Johnny