How long has your 530 been operational?

Mine is a January 22 vintage and works well. (My old 520 still works too although it really needs another new battery).

April of 2022 for me.  Except for a very few normal quirks, it works great.  I'm stupid careful with the battery, try not to ever charge above 90% or let it drop below 50%.  Doing my best to keep the battery from being the failure mode.

I'm intrigued by an 840, having both buttons and touch screen.  Touch screen would be so much nicer for the maps when mtb'ing somewhere new, but I also don't want to give up buttons.  I really don't need any of the other new features.  I keep reading the x40 forums and seeing the various problems so I'm not motivated to spend the money.  I don't have sensor drops, elevation seems spot on, gradient is slightly laggy, but who cares for mostly mtb.  I spend most of my time focused on riding, not staring at the 530.  

Even with "just buttons" the 530 has allowed me to ride completely new trail systems blind without a guide, so it has been a great asset for me.

I got mine in September 2021 and it has worked perfectly and battery still in good condition and it gets a lot of use. By my records it has done 23,605 miles since that date and 1800+ hours. I have even used it for running and walking.

I also use a Garmin Remote with it so when I am riding, I rarely have to touch the 530 and if if I did have a touch screen, I would still use a Garmin Remote and its extremely rare I get sensor dropouts and if I do, its only for a few seconds. But, i also never connect my phone to it as I cannot see the point of doing it which has been revealed to be a cause of sensor dropouts.

It has also been used on multi day events like Paris Brest Paris and London Edindburgh a a lot of other 1000K+ rides and not turned off for several days and recorded everything perfectly and no "Crashes" etc

But, as for the firmware etc on the 530, it has too many bugs but I can work around them and I have no plans on updating as all I would be doing is buying a more expensive device along with all the bugs that it has.

Indeed some of those earlier devices 520 / 530 were very stable, much much more than more recent x40 & x50. A number of my club members were doing the 2019 PBP and had 520 devices (not plus the original). I managed to cram a map for the whole 1230km route into the available 60mb using bbbike.org On-Road format (no land cover, no routing, no street names) and the whole course route in stages. All worked for them, no crashes etc and several of them kept it running for the 90 hours.

I have just dug out my old 305 out and it still works and from I can recall, despite not having maps and you just followed a "Bread Crumb" trail, I would still be happy to still use it  for some rides if I had a mount as all the ones I had broke.

Likewise, I still use my "800" occasionally and a few years ago fitted a new battery which was a simple job to do, it might have a lot of bugs in it, but, its reliable.