To sum up.
1) 'cu' is a part of Lojban that is not going away and that needs to be learned even if only for reading things from yore.
2) 'cu' is more efficient and more informative than mere terminators in the place where it occurs
3) It is arguable that learning 'cu' before the terminators decreases the students' understanding of terminators, or, at least makes them harder to learn.
4) It is arguable that learning 'cu' first has no significant effect on student competence with terminators nor in their ease of learning.. (the null)
5) There is presently no way to test 3 (and 4)
6) Until there is (and maybe even after), people will use whatever method they are comfortable with and have found
successful.
BTW xorlo is not the worst thing to happen to Lojban (it is, after all 90% right, or better). The worst thing to happen to Lojban is the mass of RHE, elidable until you need them but disastrous if you don't see you need them or make a mistake in using them. I really do wish Lojban were really based on Symbolic Logic -- sometimes.