Well, I tested a lot, and I believe the missteps are better to have than not to have. With the amount of swords, delvers, pyroblasts, ancestral, misstep, etc... it seems to be better to have it. Played the Vintage challenge today and took 1st place with this list:
2x Flooded Strand
4x Polluted Delta
1x Tolarian Academy
1x Strip Mine
3x Underground Sea
2x Volcanic Island
2x Island
1x Library of Alexandria
2x Notion Thief
1x Blightsteel Colossus
2x Dack Fayden
2x Jace, the Mind Sculptor
1x Ancestral Recall
1x Brainstorm
3x Preordain
3x Mental Misstep
4x Force of Will
2x Mana Drain
1x Ponder
1x Tinker
1x Time Walk
2x Flusterstorm
1x Vampiric Tutor
1x Demonic Tutor
1x Yawgmoth's Will
1x Gush
1x Treasure Cruise
1x Dig Through Time
1x Timetwister
1x Sensei's Divining Top
1x Time Vault
1x Voltaic Key
1x Sol Ring
1x Black Lotus
1x Mox Jet
1x Mox Sapphire
1x Mox Pearl
1x Mox Ruby
1x Mox Emerald
1x Mana Crypt
SB:
2x Sulfur Elemental
2x Ingot Chewer
3x Tormod's Crypt
3x Grafdigger's Cage
1x Toxic Deluge
2x Hurkyl's Recall
1x Mindbreak Trap
1x Arcane Laboratory