If your source content is 30FPS, rendering it to 60FPS or anything higher, doesn't make much sense. More frames in the clip means more decoding (DXV decodes on the GPU), but every second frame would then be the same as the previous one so double the work for nothing. Using double the disk space. Your 60FPS projector can already show 30FPS content on it's own.
If you can create your content all the way in 60FPS, then rendering it to 60FPS is nice to be able to do. It would give smoother movements, but also needs more power to do.
You could want to choose a specific frame rate if you'd want to play your clips synced to SMPTE for example. Then you'd create your content in the same frame rate as your SMPTE signal.
You can get the smoothest playback if the refresh rate of your output device is a multiple of footage frame rate. But I have to note that Resolume rendering is not tied to the output FPS. it can happen that a frame doesn't render in time to be displayed, for some reason like disk io bottleneck or GPU load.
You'll see the FPS display in the preview monitor go lower if you're reaching the limits of your hardware.
I'd recommend keeping your composition frame rate above 30, load wise.