Avenue won't benefit a lot from it. We are not using too much RAM as all video is rendered on the GPU.
Only the audio engine uses some RAM, but it's never that much.
RAM is used a lot when recording, video is cached in RAM and written to disk by a background thread. Sometimes the background falls behind an the amount of RAM grows steadily, especially when recording on a higher resolution. So if you often record on higher resolutions then upgrading your RAM is helpfull.
Woud be nice if you could upgrade your video card Memory that easily, that would certainly help.