FWIW, most of my lenses are oldish Sigmas which are as "tough as old boots" - I know "from experience" with those on the GX-10, K-5, K-3 x2 and the K-70. All of those bodies have taken a tumble or two (some quite "severe") and the lenses work as well (which is very well!) as they did when I bought them (3 of the 4 being "at least" 2nd hand at the time).
E.g, the 1st gen 17-70, mounted on the K-70, flew out of the rucksack on my back and landed 6ft away on the carpet - both body and lens survived unharmed!
OTOH, I am very careful with the 55-300 PLM which is reputed to be somewhat fragile at times.