Very much agree on build quality. I mostly use their mouses and their rubber side always wears out after a couple of months and if I'm lucky with that, I get the common double clicking problem with left click. Thankfully their customer support is amazing and they send replacements without too much hassle. (They even sent me a new mouse once even though it was out of warranty.)
I've had quality issues with some of their previous keyboard mouse combos, particularly bluetooth mice and perishing rubber.
However currently I use a M325 wireless mouse and its very tough. Carry it in my dusty laptop bag, dropped it a few times - no problems at all. No issues with rubber degradation. Highly recommended and works with unifying receivers.
Also, once I broke my mouse, gave them a call and said "We are sorry that mouse is not in production anymore... So I will send you the newest version for free (80 euro price tag)."
I've just been unlucky, I guess. The longest Logitech mouse that lasted me was Logitech MX500 (around 3 years), which is funny because I also had top of the line Logitech mouses (MX Revolution, Mouse MX etc.). They were usually the least durable ones.
I believe that's fixable, but I don't know how hard the fix is. I wouldn't advise you to try to fix it on your own unless you know what you're doing, or you've already contacted their customer support. Don't hesitate to contact their customer support even if your mouse is no longer under warranty.
