I have tried my mini mainly in urban areas lots of buildings and cellular towers but I generally fly above them say 10-15 mtrs and the transmission is very unreliable . For instance I tried it once it went upto 1km and the next day in the same direction with everything remaining same like my antenna,wind , height,etc it couldn't go beyond 300mtrs with a warning signs like wireless interference, weak signal and then RC disconnected , hence making it unreliable with the distance.
And I read the article which you had suggested and it does say that occusync 2 is better.
Well, what to do .
Budget is not an issue ?
All this info makes a clearer picture.
I'd avoid flying closer than say 30m any sort of high voltage power lines, cellular towers, large buildings with any drone.
It's simply dangerous to expect any signal to be totally reliable in all cases like this.
Ocusync 1.0 on the M1P / MPP on 2.4ghz still has the intelligent switching between 3 transmission channels, and picks the best one for the circumstances.
Even though the Ocusync 2.0 has 1080 over longer distances, I've never had a change in mine up to 1km, and shorter distances where there is any sort of tree or terrain coming into play.
Here's another good article re signal frequencies and pro cons, but this one also covers differences between DJI wifi, ocusync 1.0 and 2.0 and their Lightbridge (found in other various models).
DJI Transmission Systems – Wi-Fi, OcuSync & Lightbridge Drone transmission systems can have a huge effect on the capabilities of your drone. They give very different results, meaning you need to pick a transmission system that’s right for you when selecting your drone. DJI use three key...
www.heliguy.com
Personally, I think you'd find a major improvement in flight capabilities (distance and resistance to interference) with the MPP, far and above the wifi mini, spark, air.
Whether the extra 5.8ghz channel in ocusync 2.0 would help if you really want to / have to fly closer to interference sources, I'm not sure about if that would assist at all there . . . I'm not sure, but assume again ocusync 2.0 would switch between 2.4 and 5.8 depending on best for the surroundings.
If you want the ocusync 2.0, and as stated no probs with the $ over the earlier MPP, then you can choose the better camera on the Pro (mostly better photos), or maybe the Zoom with it's relatively decent optical zoom, which means you can stay back from some places, and still get decent photos.
The zoom use in flight is not without some minor issues though, mostly exposure change if zooming in when taking video.
Best to get the zoom where needed, exposure right, then start and stay on that zoom level for the clip.
I know, it's hard to make a choice when presented with these sorts of options, and the best thing sometimes is to err on the side of caution, and go with what you think is better, even if you don't really need it.