I used to take gabapentin 3 times a day. That was rather annoying. Then my pdoc reduced it to 2, which was much easier, then for other reasons switched it all to nighttime. I find that I have no bad effects from it if I take it all at nighttime (600mg) and my anxiety during the day is still lower.

I'm not sure if it does much for mood stability, but it works wonders for anxiety. The only bad effect I have from it is if I take 900mg or more, I have some concentration issues. Beyond that, the 600mg just makes me sleepy. Which is fine when I take it at bedtime. I just don't drive once I've taken it, and I'm fine by morning.

If you are worried about side effects, I think an xr would be worse, not better. It would probably make the effects last longer. Instead, I would suggest discussing with your pdoc if you can take it all at night so you sleep off the effects. They have a 300mg capsule so you could just take one pill.