If you're in a refarmed area like I am, you won't notice a difference at all between the RM-984 and RM-985 on T-Mobile. How do I know? I have both in my possession right now

. I know that sounds odd, but I was curious about that very thing so I picked up both. I can take a picture of them if that's too weird to believe lol.
I use HERE Drive and stream a bunch of video. Haven't noticed a difference at all between H+ and LTE, and the speed tests I've run have corroborated that. I even get faster H+ speeds at times, probably because the LTE network is congested. Upload speeds were better on LTE though. Paying attention to "up to" speeds is misleading, because you'll almost never get anywhere near that number. Real world speed tests are the only thing that'll give you an accurate assessment.
I'm in the process of testing just how much longer battery life is using just H+ on the RM-984 (and setting max connection speed to 3G) vs using LTE on the RM-985.
In short, both models will work just fine in most places. RM-985 will give you LTE, though battery life should be slightly worse. My advice? If you find them both for the same price, pick up the RM-985. If you can pick-up the RM-984 for $50-100 cheaper, it's probably worth the savings because you won't notice a real world difference with network speeds.