I've successfuly switched both my 940s to LED taillighting. Everything is significantly brighter. Just doing the backup lights alone is worth the cost and effort.

There are a number of brands out there and prices vary from expensive to less than the price of incandescents if you buy from the likes of Aliexpress and Temu. Just be sure to pick ones that have a decent number of SMD LEDs pointing backwards, not all pointing out the sides.

My personal choice for brakes was the Auxito 1157 with the five SMDs on the end that others have recommended here (there are other Auxito 1157 designs I haven't tried that may work as well or better), which you can often get for under $10/pair directly from Auxito in China incl. shipping. Always get the LED colour that matches the color of the lens it's behind, otherwise other wavelengths are filtered out and the bulb won't be as bright as advertised. For the dual element 1157 bulbs, almost any LED will have the park light element considerably brighter (a perpetual problem with our Volvo reflectors, especially as they age). In general, the brake light element is also brighter, but not twice as bright as the park light. Bulb running temperature is of minimal concern.

As for the bulb sensor, after a few growing pains I've now got no problems. For the first few months the bulb warning light occasionally went on for short periods, so start by cleaning up the holders, taillight assembly contacts and loosen/remake the black ground wire at the chassis, ideally using a suitable electrical paste. Even after doing that, I occasionally had intermittent warning bulb issues until I re-flowed the solder joints in the bulb sensor relay, paying special attention to the brake light circuits on the middle board. For many months now everything is working fine in both 940s.

Note that if you use LEDs in taillights then ideally you will also do the 3rd brake light to help minimize bulb sensor issues. The bulb sensor design compares the current of one brake bulb to the combined current of approximately 2/3rds of the other brake bulb plus 1/3rd of the 3rd brake bulb. When that comparison becomes significantly unequal then the reed switch trips and the warning light goes on. If the two main brake bulbs are well matched without significant voltage drops through the wiring and contacts then an incandescent 3rd brakelight seems to work fine, but obviously you're pushing the balance of the reed switch, so highly recommended to use an LED 1156 3rd bulb.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now