I suggest adding a generator you can teleport to (or use Recall/Dark Summoning with the teleporting conditions, =6 seconds not attacked), so that you can get to key-points more easily.
Make the generator cost 3 energy, but teleporting itself is free (or cost only 50), since the generator itself costs gold and the energy could be used for other generators.
Would be awesome if you manage to build it near the enemy base, and i mean real close to it.
Or having them near important shops, or other points.
I like the idea of this "Recall" Generator maybe building a "Portal" Generator with that you can create a Portal where units can walk trough.
Since it got no defence mechanism and needs to be placed in forward positions, it may get killed quickly anyways, so I vote against limited uses and death... but maybe a long CD, like 2 or 3 minutes.
Hrm...It sounds interesting, but think about a Command Tower and redirecting the creeps through it...If you can get through to build the generator, skip the other outposts and attack the main base. Maybe limit the range of the teleport? (This is assuming it's a 'portal'-ish generator, not a summoning one.)
"L4D2 promises to set a new benchmark for co-op games. . ." Like L4D promised to hand us new maps, survivors, and zombies? We've seen how that works.
How about adding teleports to the mills on Candleburg, like on your alter, except for the controlers of the mills, because instead of walking all the way across that huge map.(=D)