You'd be silly not to stay with Marc if you're stopping in Paris for any length of time. Marc's flat is very stylish and welcoming, with a comfortable bedroom (with fans!), a fully-stocked kitchen, and very clean bathroom/shower room. Marc himself takes the cake though - he is incredibly friendly and accommodating, giving recommendations for food/things to do, place-settings for breakfast, and keeping some foods available for snacking (asking of course that you pay for it with an honour system). His level of hospitality is not common.
The location is great, not even 5 minutes from the metro and restaurants outside of the tourist-heavy region of Paris. Marc keeps a great deal of information on the city available in the bedroom for travellers.
Again, you'd be silly not to stay here.