why even deal w/an OEM system that is ham-stringed from the get go? Why not just go aftermarket and benefit from certain features not available on OEM units? You have the simplest, least complicated radio setup, so that will make replacement of said radio easier (easiest). There are plenty of double-din, full, touch screen, CD/DVD (and NAV in some cases), that for the same or less prices of your ebay OEM units, will perform better.
I don't know about you, but Crutchfield is my go to if and when I need to upgrade/replace any car audio piece (I have zero faith in local big box electronic stores). I changed out our 04 Pathfinder's OE Blose headunit w/a simple JVC unit from Crutchfield because of the CD player skipping. Other than some sonic issues (reduced bass) caused by the new headunit and Blose amp nuances, the new unit did just fine. Sure, I lost a 6-disk in dash CD player, but you can only listen to one CD at any given time, but the CD skipping was eliminated. Since everything was plug and play, when we traded in the PF on the CX-5, I just removed the JVC unit (and assoc harnesses, steering wheel control adapter, and trim pieces) and returned everything to stock.
Once the stock unit was back in, the sonic performance returned to "normal".
Despite a lot of big name companies (Alpine an Clarion) leaving the aftermarket headunit business to pursue OE infotainment design, there are still a slew of great companies making some great car headunits that put a lot of the OE stuff to shame because they aren't hampered by cost and/or design constraints. Remember, those companies WANT you to buy their headunit and ditch your under performing OE one.
The only real problems w/going aftermarket is when you start out w/a premium system, like Bose, HK, SONY, Mark Levinson, B&O, B&W, etc. etc. A lot of times, aftermarket stuff won't play well w/the special impedances and odd amp signal input/output voltages like the JVC did in our Pathfinder. For the best performance/sound, it is best to just rip out all of the "special" crap and start from scratch.
However, you don't have to deal w/that as you have the base radio; making it way easier to swap in an aftermarket headunit. Now, you might need to get a steering wheel control adapter if you want to keep your steering wheel audio controls, but besides that, it should be a straight forward install.
This is just my opinion and the route I would go. However, since I have a 2016 Touring, chances of me replacing the factory headunit (non-NAV) are slim. Unless there is a headunit out there that can out perform the factory one and integrate the control knob/steering wheel controls/backup camera, I'm not going to do it unless my hand is forced.
On the other hand, I'm really anxious to replace all of the speakers (6) w/some that are less compromised by OE budget constraints. And all of these (Infinity/JBL) speaker sales that Crutchfield keeps having, makes it very tempting to buy 6 brand new speakers just becuase.