I purchased my low mileage R26 nearly four years ago. It has been most enjoyable and very reliable. I have not experienced the multiple squeaks and rattles mentioned in your report. At just under 80,000km, the car is still good and tight and looks almost like new!
In my time with the R26, apart from road use, I have used it for track events over twenty times in three years. It has therefore consumed a couple of sets of tyres and brake consumables. I haven't 'chipped' it or modified it in any way. It has been absolutely 'bullet-proof' mechanically. It gives the impression that it could happily spend all day, every day on the track!
Petrol consumption depends very much on the way it is driven. Track use yields about 25 - 30 litre/100km and highway cruising about 6.5!
Appearance wise, I don't mind the 'big bum' but I don't like the bright yellow paint and the stickers. I would prefer something a bit more discreet. Rear leg room is a bit tight and the lack of rear doors makes the entry for rear passengers inconvenient. However, I rarely carry passengers in the back. The lasting impression is of a car which is very rewarding to drive, so I'm willing to forgive it most things.
The later model RenaultSPORT Meganes are more powerful and therefore faster. However, the R26 still significantly outperforms the latest model Golf GTI and other such 'competitors' on the track. I love the gentle and effective action of the mechanical limited slip differential - it is really well set up. Overall, I love my R26!
When I ultimately do replace the R26, it will almost certainly be with a new RenaultSPORT Megane.