With explorer in Ascent you're ahead 0.5 points per dollar so would need to spend $150k to break even on missing the Explorer sign up. I wonder whether Explorer will continue to be the better option in Ascent should Amex implement their planned changes to Ascent and whether Gateway will also be restructured. Sounds like the most conservative option is to try to put Explorer on Gateway, possibly get the Bonus then figure it out from there.