Low Latency Kernel Downsides? [duplicate]

Does it cause compatibility issues?

It should not, but it since less people use it, it is a little bit less well tested.

Does it reduce the lifespan of my hardware?

No. This kernel is optimized for a lower latency (versus throughput). Running the -lowlatency will mostly change in which order the load will be handled, it will only change the load quantity by a small amount (because switching task is a load in itself).

Since the workload is mainly the same, I expect the wear to be mainly the same. It is perhaps a good idea to look at the temperature (of the CPU, HDD and mainboard) if you switch to the -lowlatency kernel, since it's possible that some power-saving features could be disable while using this kernel.

... but I am wondering if it has any downsides?

The -lowlatency kernel is somewhere between the -generic kernel and the real-time linux kernel.

According to this wikipedia article, real-time operating systems are optimized for the response time and not the throughput. The -lowlatency kernel will be able to switch to a task faster and more frequently than the -generic kernel.

The -lowlatency kernel is thus recommended for studio work, because you need the computer to respond as fast as possible at your requests (i.e: MIDI events and so on). The -generic kernel is for when you want to browse the internet, while the same computer is serving the files for the whole office.