I don't claim to be wise, and I my Rekluse experience is on dirt bikes and a DRZ, not the Terra yet. But here is my opinion:
1) Someone told you that you do not have engine braking during a decent with the Rekluse. That is not true as long as it is set up correctly. If you are experiencing engine braking, then the wheel is being turned fast enough that the accompanying engine speed will be above idle (thus the clutch will be engaged.) You won't have any if you kill the engine though. I prefer my engagement point as close to idle as possible, but you should experiment.
It is possible that the surface is loose enough that the rear wheel would be skidding more than turning in which case you could lose engine braking. But if that is the case, then the engine brake becomes less effective than the rear brake anyway, so no loss.
Unrelated side note, but also, practice using your front brakes on descents if you can. Most of the weight (and available traction) is going to be on the front wheel. I've had so many "experts" tell me that you shouldn't use the front brake on steep descents, but I don't know where that nugget of advice comes from. I find the front brake to be the most effective tool for controlling descent. I'm sure there is a point where a descent is so steep and/or the surface so loose that perhaps front brake isn't advisable, but I with my meager skills have probably looked upon such descents and considered them "end of trail" obstacles rather than challenges to be conquered...
...what he said...
O.K., I just wandered in here too, but I'll toss this in. I had to relearn dirt riding after a 20 year hiatus, but it came back to me fairly well.
That said, when I'm rusty I'll find myself stepping hard on the rear brake (panic), especially downhill....S-L-I-D-E....
Back in the day front braking was a big no-no. 'You wash out the front!".
A lot of desert racers threw away their front brakes completely, not that they worked that well to begin with...
To this day people believe the same.
Modern riding shows just the opposite in theory. Using the front brake on both dirt and street allows more tire contact patch on the ground, resulting in
better traction as
gullywasher said.
You just need to learn a more refined approach. Downhill or or slamming a turn, front brake is your best friend.
As a point of reference, I have a 'slipper' clutch on my KTM 450EXC that was installed when I bought the bike. Thought I wouldn't like it.
I LOVE how the thing works.
It may not have the snap of a standard clutch bike, but I like how it revs-and-catches in a smooth linear fashion. I like how it lets me descend without fret.
Overall it's made me a better rider.
I've torn into the clutch pack and after many miles it shows zero wear (plates maesured against a new clutch pack).
Only drawback that I see is the bike is near impossible to drop into neutral at a stop. That and the bike needs to warm up the oil before it's dropped into gear.
I have no experience with the Rekluse though...
My2Sense