McGizmo's Aleph system is fully compatible to the SF E-Series and you can use an Aleph head on your E2 body for extended throw.
The candidate would be the Aleph1 head with a DownBoy or Wiz2 driver set at approx. 1000mA running a LuxIII. The head looks like this:
... and is slightly wider than the E2e head. This combo will outthrow the E2e, but don't expect a breathtaking difference. A big improvement is the fully regulated runtime of roughly 90min though ... and the luminous flux is roughly in the same league, too.
SF E2D:
Aleph1 T-bin at 917mA:
And outside:
SF E2D:
Aleph1 1000mA T-bin LuxIII:
If you really want throw in an E-Series light you can get the Aleph3 head looking like this:
... which is a bnit on the large side but destroys both of the above mentioned :devil:
bernie
EDIT: and you can replace your SF tailcap with an Aleph tailcap housing the McE2S module that transforms your light into a 2-stage light with a low-mode.