Hi, I am looking forward to the 8500 mah as well!
With regards to the 3500 mah, I have to say it is pretty cool! I thought that it was going to add a ton of bulk to the phone but it is actually not that bad of course it is going to add some bulk as it is essentially an additional battery.
The 2 biggest reasons I was hesitant to upgrade from my note 4 was no removable battery but the Zerolemon 3500 mah case really does the trick and the expandable storage (which I was able to fix with the OTG cable to micro SD). I ended up adding a Dbrand skin to the back of my phone for protection despite my concern about the battery scratching the back glass, but now that I have the Battery Case it is not abrasive like I thought it would be prior to purchasing.
There are many times when I am not near a charger as my daily commute is over 2 hours each way (if the trains have no delays which is rare) and I have found that I can get a full day of HEAVY usage, I mean streaming videos round trip for my commute and using it at work all day and have not had to charge it until I get home in the evening and even then I have between 15-30% battery power left. I like the idea of the pass through charging but I won't use it that often as I have external battery packs and I don't want to take away from the phone battery.
The case itself is pretty good as well and it does fit the phone with the battery in it nicely but like the last user said, it is not as protective as say a UAG or an Otterbox of course but that is the tradeoff and a decision you have to make if you want to use the Zerolemon Note 5 battery pack. For me this is definitely worth it especially when I am stationary for a long period of time.
So yes there are ways around the non removable battery and the lack of SD card expansion, the SD card expansion issue has been discussed many times in the forums, but there is not alot of info on battery packs so overall, I do like the 3500 mah case and would recommend to people that can't plug in often and are looking for some extra power during the day especially when you are stuck on the train or at the station because of delays and such, however I can't wait for the 8500 mah case!
I hope this is helpful, Please let me know if I can answer any questions for you as you all have been so helpful to me in my decision making process!
Thanks!