Hi, I've been using SL1 with my Rev. A HDD MBA and it runs fine, without any tweaks (i.e. Time Machine and Mobile Me Sync running on background, wifi, screen sharing and file sharing enabled).
SL3 will run even better since it's more powerful and can handle more of SSL processing. I think it'll handle the additional samplers and input/output nicely.
Go for it. I'll upgrade ASAP.