All in one loan loan vs conventional loan

Starting up the All in One Loan conversation again.   Just lost the rate to a home that I was “locked” into from last Feb.  looking at other options and the AIO was presented to me.  The adjustable interest rate is what concerns me.  Over goal is to use this for an investment property and to expand in the future.  Would you lock in at 6% now for a conventional or take the AIO with its advantages and adjustable rate starting at 5%.  A lot of people seem to be in favor of this loan, but I am trying to find the downsides as this is the first I have heard of it.  Thanks for any insight.