I think Pioneer is just a better card than Parade anyway. I think doubler cards are more interesting when they remain totally dependent on their targets, and making a doubler card with any of the vanilla bonuses, but +Card especially, takes away from that. Royal Carriage, Procession, King's Court, and Ghost all put some twist on Throne Room that doesn't really free it from dependence on its targets.
Ghost, Procession, and Royal Carriage all put some twist on the question "is Throne Room good here?" that makes it slightly tricker, except maybe in the case of Royal Carriage where it is somewhat easier (don't want to spend 5$ on something for it to spend all game on your tavern mat though). Deciding whether Parade will be good enough will probably be easier most of the time because Parade Parade collisions usually dig into an action to play and even when they don't they cycle your deck forward to the next iteration where you've cut your disaster risk even lower with your purchases.
On the other hand, Pioneer, which I think seems best at 2, seems like a very interesting card to me. I mean. It's Scout with +1 Card instead of +1 Action. Isn't it? I love me some Scout man! But seriously, aside from filling the hole in my heart from the lover I never want to forget, Pioneer offers a way to avoid buying a Silver that you know is slightly better than Pioneer right now and will be worse than Pioneer later. You'll often get to put a Silver on top and draw it, the times you can't, the Silver is probably already in your hand, and you can discard all the looks to cycle that Silver into the reshuffle faster. In the early game, you buy Pioneer as a pseudosilver to ensure you keep hitting 5$ consistently to buy some key 5$ card a lot. In the midgame you buy an extra village to pair with the Pioneer so that Pioneer is no worse than Great Hall, maybe a little better if trashing has been a slow process. (Note that buying an extra village doesn't make a Silver stop being a stop card. Buying a village and connecting with it make Pioneer a nonstop card that occasionally snipes a stop card). In the late game when you are forced to have provinces in your deck, this can just be a Smithy! (Not an exciting ending to the story if this stays at 4$ but exciting if its price is adjusted down.)