I highly recommend Federico as a wonderful host who was always ready to answer all my questions. His lovely flat is located very close to both train and underground station, local market with huge selection of local food and finally not that far from the Colosseum.
Just one thing to keep in mind - although the building is not on the main street, it tends to be quite noisy in the night, so buying in advance a pair of earplugs would be a smart move :)
Overall, I would definitely stay again in Federico’s flat.