In my opinion, I don't like this change. Imladris' Stronghold reflects the fact that the Elves helped the remnants of Arnor to finish Angmar off, Glorfindel was a key part on defeating the Witch King, and both this outpost and the Earnur summon reflect the aid that Arnor got in their final days. Furthermore, the Dúnedain Rangers were never a lot, in the Arnor timeline they should be few as they only were part of the Cardolan barrowguards and the Aranarth rangers, I don't think an outpost for them in Arnor is fitting.
In Imladris, just making the already underpowered Glorfindel even harder to recruit would harm the faction, and I think the Dunedain outpost fits because, even if they are not a lot, Dunedain Rangers are on the side of Imladris, and Eriador as a whole. Imladris' external plots represent the different people of Eriador, the Hobbit Farm representing the Shire, the Lindon Watchtower (that fits both in Arnor and Imladris) represents Lindon (of course), and the Dúnedain Outpost reflects the fact that Imladris and them are allies, unlike in Arnor, where the Rangers are just a small part of the faction. The rangers have a bigger purpose in Imladris, both gameplay-wise and lore-wise, as the protectors of Eriador and the way for Imladris to produce cheaper units.
So, in my opinion, this change would harm both factions, losing Glorfindel and his Riders in Arnor, which are useful in gameplay and fitting in lore, and making Glorfindel be worse in Imladris by making him only recruitable in an Outpost. Also, I think the way it is right now includes more elements from the lore, with Glorfindel helping the Men of the North and the Dúnedain being allies with Imladris, but not just a part of their army (which I believe the settlement would make them feel like, like the Ithilien Rangers.)
EDIT: What I think could be made to give Arnor some more variety is making their Rangers able to change weapons between sword and bow, if they receive Aranarth's upgrade. That way they'd get other elite unit without changing a lot.