I am a little late for this party since I saw the "decision made" reply there. But for others searching for solutions to this same problem...
I use the Opus BT3400, which is (according to what I found the on the web) BT-3100 with V2.1 software for the USA. Overall, the BT3400 works rather well. Shows the actual charge current, accommodates overly long 18650 (*72mm)...
The issue to me is the pulse charging/discharging - it makes comparison a bit more difficult. To illustrate with example, if the BT3400 tests the capacity to 1000mAH, it was tested under pulse discharge. If and how it manipulates the number to a steady-current discharge capacity is a mystery to me. My independent tests (with fixed resistor load) would show around 800-900mAH (80% to 90% of shown). I don't know for sure if it was due to a pulsing discharge (v fix load), or that my fixed resistor load is varying the current. In any event, I am using the BC3400's number as the number I used for load
Second issue is the LCD is not as even as I like. Cell 1 part of the display has a small smear visible only when back-light is on.
Other than that, all good news. The ability to charge NiMH is great. I pop my AAA/AA in as needed.
*72mm:
When I emailed the seller and asked if it can fit a cell that long. He was shocked I have cells that long. Well, most of my repacks with protection (at the time) topped out around 71mm. I have since repacked all of them to top out at < 70mm. Then, I got a repack from FastTech NCR18650BE with proctection board, 71mm +- a little... They are the best batteries I have in my battery box now, but they are the longest I got.
So, the fact that you can jam a 72mm cell into the BT3400 is quite a plus, at least until you can get your packing techniques better. And the BT3400 wont be the one limiting your cell length when you hunt for repacks to buy.