I do both , so feel somewhat qualified to comment on your viewpoint.
There is a great deal of crossover in skills,methods, risk, mentality,attitudes and 'some' shared ethics
There are also some glaring differences in how each group goes about its business.
There is no doubt though...that each group can benefit, in its own aims, from cooperation with the other.
Most BASE jumpers look at UE , particulary High Stuff advocates, as a threat....due to the divergence in ethics on site naming, mixed with a little bit of ignorance on UE aims, goals and participants.
That said....I, as well as other jumpers , have experienced a great deal of benefit in intel, as well as cooperation from the UE community, in achieving 'our' aims.
I wouldn't say high was 'easy' there's still a fcuking great building behind you that's gonna hurt if you get a 180 on opening.
Judging when to pull on a jump that high could be tricky too - most BASE jumps are 1-5 seconds, from that high you've got some interesting sums to do to work out the delay, then you've got to remember to count...
I could be wrong, never having done a BASE jump...