I've used a 7 series and it was "ok." You still have to go back over spots which causes irritation and it gets close enough of a cut that ingrown hairs become a concern, especially on your neck area. All these issues made it impossible to use without waiting at least 2-3 days in between shaves.

Believe it or not, I've been using a cheap Philips Norelco OneBlade since it came out with great results. No, it does not get as close a razor or a "nicer" Braun for that matter, but there's zero irritation no matter how many times you go over an area and no ingrown hairs either. It can also be used wet or dry. Using it multiple days in a row has proven to cause zero issues.