Same seller as mine.
Mine still changes modes too much, but with an Alpkit headtorch I generally have all the light I need. I hope the replacement when it arrives will be more reliable.
MattHB has the same light as the one I have ordered, and has said he has no issues with mode changing, even on trails - So I'm fairly hopeful.
From what you have said, the mode changing seems to be caused by not having enough spring-force pushing the batteries together along the length of the torch. If mine does have that issue I will machine out a small metal disc the same width as the batteries (with the circumference wrapped in insulation tape, so as not to short out the torch) to put in-line with the batteries to keep everything a bit more compressed, which should hopefully eliminate the movement that it causing the mode changing.
And if
that fails, I needed a high powered torch anyway - So I'll just use it as a torch, instead of a bike light!