No, you do not get to board without a number. You get a number.....it is the number 1.
Our experience--walked into the terminal and CM offered to "escort" me to the concierge line. Thanked her, but told her that I knew where it was. Checked in at concierge/platinum line, got platinum lanyards. Asked about cost of upgrade and decided not to do it. Given boarding card number 1 at concierge desk.
Security photos were taken in the regular line, not the concierge security photo camera. There was no line at all for photos, walked right over. Photo taken (they did NOT take our boarding card!) By the time we had finished photos, boarding had already started. Security photo guy took us to the boarding area where he removed the fabric/tape thing that is used for crowd control and told us to go ahead and board (thus cutting the line totally). If we had checked in before boarding started, we would have been able to wait in the roped off concierge section.
One note..these services are available only to platinum members and people in the same cabin with a platinum member. If you have linked cabins but one is platinum, one not the second cabin will not get these perks. No personal experience with this, but we saw someone try it and they were politely re-directed to the standard line.