http://www.a123systems.com ????????????

How long do you think it would take to have a pack better than lipo ?

This type of Lipo (well, it's not exactly a LiPo as per definition...) has been available since 2005 under different names (Konion, BMZ 26650, etc.). Gerd Giese's excellent site listed and tested it in July 2006: http://www.elektromodellflug.de/akku-test/26650-x.htm (in german).
There are still drawbacks at this design, notably weight and nominal voltage, which is 3.0V/cell and full charge voltage drops in at 3.6V. Which means you need more cells to achieve the same voltage used in F3A (42V per pack). If weight is not an issue, then these cells are very good. Provided you find a LiFePO-compatible ESC!!!

A search for 26650, BMZ, Konion or similar should bring up several threads about this type of cell.

Regards,
-Fabrizio

the 123 works extremely well -once you understand its true advantages and limits
I use both LiPo and 123 cells for power -
If the plane is designed around the 123 - it is prefferred setup --to me .
until you hit about a 3 lb (1.5 kilo )all up weight the LiPos are better .
I am not talking about competition intended models - just nice, fun to fly ,high performance types.