No. I don't want people being able to teleport past my energy fields. It's possible to set teleport macros in UOAssist, so any prepared guild could run up, hit a button, and jump inside to wreak havoc rather than having to slowly beat down the defenders of the fields.
Thus, being able to teleport would kill any method or motive to defend the bases as it's deadly exhausting (and boring), and the raiders will always be able to gather and attack the underdefended base.
Sieges should give the defenders the benefit, teleport would eliminate that.
That said, this can probably be fixed with a tweak...