For all it is worth, after seeing an explosion of stretch related problems, I have to say that in my experience with LXDE there has been no difference between my pre-Saturday 17/6/17 experience and my post Sunday 18/6/17 experience.
Despite of what is commonly advised here, I switched my Sid installation to testing and after an update/upgrade procedure I believe the only difference is some cerificate update, otherwise it stayed the same. It might be my own combination of packages but there seems to be no difference to current testing and previous (pre-18-6-17) sid. Surprised? Not at all!