Good question! I should probably post the answer as a cautionary tale...I would LOVE to finance this with Fannie Mae but....
We tried to refi this property with the FNMA 5-10 properties program a couple of years back. I was going through a local broker who was working with a couple of lenders who do FNMA 5-10 loans. Everything was great until the appraisal came back. The appraisal value was good, but the lender rejected the loan becuse the appraiser had used duplexes as comps, rather than triplexes. The fact of the matter is that there are very few triplexes in the known area--probably within a 5 or 10 mile radius--and none that had sold within the last 6-12 months as required by FNMA. The entity wanting "triplex comps" was the lender--not FNMA; I think they were still a little skittish, erring ridiculously to the cautious side after the crash. They didn't even ask the appraiser to go back and try to find triplex comps; they just said no.
After going back and forth with the broker, we decided it wasn't worth taking another chance with a different lender, paying for another appraisal only to get the same sort of outcome. So we decided we would stick with the commercial note.
I'm hoping the commercial rates are a little better than they were 5 years ago.