I think this is definitely an interesting proposal and I especially like the idea of the money going where you feel it is needed or deserved.
The main concern I'd have is how many people would actually fill this out and how/if they'll change their choices.
Will people be forced to fill it in every year?
Will they fill it in at all?
Will there be a default selection? Like all to RTÉ, or maybe an even split between all options?
If people don't have to make a selection every year, will they just choose once and never update or change it because it's a hassle?