Most banks are pretty tight when it comes to forced appreciation even though it's natural for a property that's been renovated to command better rents.Even some portfolio lenders require a 12 month seasoning to use the appraised value. 

Ok, next challenge based on your description, I think, is finding a 6+ plex to buy.

Accounting system of some sort (Quickbooks), and then your biggest challenge will just be marketing and getting customers. 

Natural appreciation should be the butter, not the bread of your profits. 

Being analytical in nature I have to fight against the analysis paralysis when looking at non-performing loans because its easy to find things wrong with them,  but that's why they will sell at a discount. 

Challenges?

As @Zack Karp mentioned, it can be very challenging to pull of the perfect "BRRR" on a 203k loan.

An appraiser will view the property and if the repairs are extensive they can be called out and create challenges.

1% rule is definitely challenging to find in this market and depends on a lot of variables (price range, condition, condo vs single family, neighborhood, town, etc).Going slightly outside of Charlotte (Concord, Gatonia, etc) like @Joshua Davis did.

Challenges?