That’s an excellent question. Unfortunately I can’t say I ever used the Oppo‘s NEO:6 mode much so I can’t compare knowledgeably. Since it was there “for free” and certainly gave me surround effect, I would’ve used it more, but I didn’t like that you have to have a screen active and go into the setup program to toggle it on and off. (Unless, of course, there actually is a way to do it from the remote that I was too dumb to ever find.)
Also, like some other Oppo owners, I’m just slightly paranoid about keeping mine going (I know that’s dumb since I’m 67 and the 105D is likely to outlive me, plus I have a 103 in reserve). It does tend to run warm and it’s relatively power-consumptive so it’s nice to only have to power it up when I really need to, for SACDs, multichannel FLACs, etc.