We enabled Fastlane on a mid-market Shopify Plus brand and A/B tested it against our existing guest checkout for 7 days (n=12,184 sessions): mobile checkout completion was up 8.4% and time-to-pay dropped about 9 seconds. Behavioral analytics showed fewer backtracks on contact fields and a 22% drop in rage clicks — anyone else seeing similar effects or pitfalls with repeat vs new users?