Gabriele did host us (a couple) in his "Romantic Flat in San Marco" during 4 nights in middle-september. The place was a lot bigger than shown on the pictures, you have 4 spacious rooms (kitchen / dining room + bedroom + bathroom/toilet + living room) and place is big enough for 3-4 people. Location is perfect, the "Campo" nearby is full of delicious and very affordable restaurants, and you are 10 mins. from San Marco. It was really good to be able to chill inside of Venice at night, and to go back home without looking for a Vaporetto or a train. We were able to do everything by foot during the trip !
Gabriele was a nice host, easy to join and always available before our arrival. Very "professionnal" welcoming, explained us clear rules about the place, gave us a map of the neighborhood, some tourist informations...
Only bad point of the place might be that it's on the street level, and given the width of Venice's streets... It's always dark inside ! We were not here during the day so it was not a problem (and the lamps are very bright anyway).
So even if it's a little more than your budget, and you're thinking about staying out of Venice's center, our advice is : DON'T. It's far better to spend a little more to be in the center than to take a Vaporetto every morning and evening (one-way ticket is 7,50€ / person... so it's worth walking !)