I am not sure that the fencer would be a great addition:
- L2 Tribes: If I counted correctly, 28 levels use a fencer. Out of them 23 would work equally well with bashers, 3 use the fencer to emulate a one-way-wall and 2 levels would require replacing a steel block (that is not necessary for removing otherwise possible solutions!) by destructible terrain. So L2 did absolutely nothing interesting at all with the fencer!
The problem with the fencer in Lemmings 2 was that the slope it made was to small.
This made the skill kind of useless and very similar to the basher. I think that if the fencer created a slope the same angle as the miner does it would make it a more useful skill.
I think having another way to gain height besides building would be nice to have.