I bought a 4plex a year out of school with FHA, so I dont see you having any problems. Also, if I remember right, you have up to 6 months to move in after buying it (to allow existing leases to expire, etc) so if you have a GOOD tenant who would be ready to move in it when you buy it, you can do a short term lease to help stash some extra cash and then move into that unit in 6 months.
My strategy is to hold on to this 4 plex, invest some money into it, i already converted a 1br unit into 2 for an extra 150 per month and will redo kitchens/bathrooms in the future. Once the market starts to bounce back and I have ~25% equity I will refi out of the FHA into conventional and no longer live there. Then, I will go buy another 4plex with FHA and 3.5% down and do it all over again.
I see this being a pretty good way to get into properties with little down and not a very comprehensive balance sheet since FHA guidelines are much less stringent than other forms.
Good luck!