In my situation, it's for a local build/staging server running ubuntu server. Things I'd like to know are:
Why I should/shouldn't use LVM?
What problems might it cause in terms of either regular server operation or things I might want to do later? (ex. partitioning)
Why I should/shouldn't use encrypted LVM instead of LVM?
What problems might encrypted LVM cause in terms of either regular server operation or things I might want to do later? (ex. partitioning)
LVM makes managing partitions a lot easier. Most Linux filesystems can be expanded these days, and expanding a partition (or Logical Volume as they're called in LVM) is a LOT easier than it is with MBR or GPT partition tables. The enhanced flexibility it provides is the main reason people use it.
When creating your set up, don't allocate all of your disk to your Logical Volumes, leave some slack. When those filesystems grow to the point they need more space, just Expand it using some of your saved space. This is a very easy operation, and unlike MBR/GPT the actual data area doesn't even have to be contiguous.
LVM does extend the code-path for getting data to actual drives, but it is very battle-tested by now. There are very few cases where I would NOT use LVM.