I see no reason for the SST40 S2+ from Arilux to be of any lower quality than Simon's. Authentic Convoy stuff is sold in many places for affordable pricing (lower than the default figures at the Convoy flashlight Store). Simon offers top customer service, custom requests and, on top of this, he does offer a 15% discount to all BLF members. To obtain such a discount you need to submit your order, which is made by selecting “other payment methods” and then withdrawing from the Alipay payment page so you don't pay straight away¹. After this you go to My Orders, select your payment pending order and submit a message to Simon kindly requesting a discount. He'll adjust the order total briefly afterwards.
¹ A glitch when buying via internet browsers may happen for the moment, resulting in not being able to select “other payment methods” as payment option. If this happens to you, order via the AliExpress application.
Unfortunately, I already bought the flashlight from the convoy store without the convoy discount and just with the new customer discount. But thank you really much for the detailed explanation. You, Barkuti seem to be of distinct value with everything you post in this forum!