Staying at David's has been really great. Getting in an out is really smooth, you have a pint of Milk and some wine in the fridge and also some really nice scotch whisky.
Halfway through our 2 weeks stay he has arranged a cleaning of the place, new towels and bedsheets and we did not have to pay for that.
Obviously, when you travel to Edinburgh, you will have to climb stairs because the City has been built around hills. Thus, a few more flights of stairs getting to David's flat in the fourth floor really should not be an issue.
Without hesitation I would recommend this flat to anyone traveling to Edinburgh.