I've also become wary of semi-soft, folding panels after a couple of failures. Some of the cheaper ones don't give a decent output from new, but my experience with better ones that even if they start out well enough, they decline over time. I suspect the repeated folding and unfolding doesn't help, although it may also be the different solar array material in semi-soft panels. I've just ordered a rigid one.
If a panel is advertising more than 170 watts per sq metre avoid it like the plague. In reality if you got 130 watts per square metre you will be extremely lucky.
Only two brands of flexible solar panels worth buying, the eArc by Sunman and Renogy. Almost sure the Renogy are made by Sunman. They are both EFTE covering with dimpled surface which harvests more sun. The surface covering makes up for their lower effeciency.