You have to not hesitate install new versions - I'm checking it in different ways and I'm trying to have smooth feature additions - not change the current code/current settings.
My extensions (Zh GM) is more that 2 years in JED, and I only two times have "big" errors. The last - it was fixing mootools dynamic query infowin content (it was broken by some joomla's new rules for mootools/ajax response from controler). I fixed it, but not clear - I added jquery support, but create ariable every time (and I fixed it immediately when recognize problem).
But - in any case - I try to fix the problem in the day, when it was found.
As for matrix report - I can do it. I can create new plugin call, and you can pass it your column sequence. But I can do that only after my summer holidays - it started after June 20, ie I can add this feature only in July
And one thing else - I add into JED in 1-2 weeks delay, and in this case you can "rollback" to previous version from JED.
- I add into autoupdate, and extension can be upgraded by Extension Manager
- but JED have previous version 1-2 weeks
- after that time (when I can support) - I post it into JED
- check forum for errors