Could anyone provide me with..

some Stepmania song packs that are equivalent to challenging, very challenging and for masters only difficulty songs on FFR? I've been told many times in the past that if I give stepmania a shot, I won't regret it (compared to FFR). Before I do that, I'll need some of your guyses help. I need as many song packs as you can think of that would help someone who, right now is capable of inconsistently full comboing VC's and is looking to make a transition from VC to FMO. I also wouldn't mind some hard songs for stamina build (hard songs megapack). I just literally have no idea what song packs to get and where to get them, and I don't feel like downloading a ton of packs just to find out that the songs are way above my skill level. Quite frankly I'm ready to make that leap from FFR to Stepmania, so if you can.. PLEASE provide me with links to these song packs, that would greatly appreciated.

Also, on a side note, does anyone know what speed 1.75x would translate to in SM? Or better yet does anyone have a conversion chart for speeds? Thanks in advance.