After reading here and there, the different experiences when has this product, I decided (in spite of everything) to take the plunge:
Configuring places: a Livebox 2 has a 3rd floor, no computer in the second (or 802.11x device) and WIFI 1-2 Post the first floor (MacOS and XP SP3)
In summary, the signal must pass through two slabs and 3-4 pieces
Without the repeater, with a WiFi software on a laptop, I effecuté mini audit of places to estimate coverage ... result: the piece "wifisé" has NO signal or very low time 2 min (from the number of slabs, parts, wall thickness, etc ...)
After a repeater configuration (max 10 min great), I recovered the same SSID, WPA2
Race Results: 40% signal (against 10% previously), the same rate as on the box, and a really stable connection (even if sometimes the intensity down signal)
The product therefore respect his contract: 10 out of 10