Replying to Full Tilt Rumor vs. Soul Sister

I have FT Rumor's right now and the tongue is #4 flex, and I was thinking about getting some Soul Sisters which are #6 flex tongues because they're super cheap online. I couldn't think of anything else from my parents for christmas so it was all I could come up with. I know that I can easily buy a 6 flex tongue and just swap it out, but I was desperate to come up with a gift haha.

Anyone have the Soul sisters and can speak at how great they are compared to the rumor's? Or vise versa? Or want to tell me there's literally no point in getting them if I already have the rumor's? I have increasingly become an aggressive skier after skiing more big mountain and less park and my boots have been frustrating me a ton. Hoping the soul sister's would help at least a little. Any help is appreciated thanks!!!!