I really enjoy lightflow as well.
I do use a custom flash rate as well. I found that I like 1000,750 best. I wouldn't like 50,3000 at all as then I'd have to stare at my phone for up to 3 seconds to confirm whether I had a notification or not. To each their own, which is why it's such a nice application.
I wish there was a way to override app notifications rather than have to turn them off in the app itself. For example, with the ESPN app, there's NO way to disable audio and vibrate notifications. I was hoping that setting audio to silent and vibrate to none in lightflow would suppress those notifications. The developer of lightflow (who is very responsive) confirmed that's not the case and they have to be shut off first in the app or you'll get double notifications.
Also, FWIW, I see no evidence of lightflow using significant battery power (at least not once Samsung fixed the notifications on US phones with the JB update). I know that's a frequent complaint of lightflow.