TiLP2 1.14 or higher works with OS above 1.4, it can install any os but you can't get files off of it.
In Nspire mode, TILP II 1.14 won't communicate with Nspire OS 2.x at all (TI made a gratuitous incompatibility with all of their previous USB calculators and cables by changing the USB endpoints), and variable transfers won't work well with OS >= 1.7 (since, again, TI changed something in the protocol).
TILP II from SVN can, however, communicate at all with Nspire OS 2.x in Nspire mode, but nothing has changed wrt. variable transfer.
I hope the problem with the 84+ reported here can be reproduced easily with older OS, because I'm not really keen on using thar crappy OS 2.1 on my calculators, even if there's Nleash.