Yes, so did we, but again its a bit different in a stadium where everybody is near an exit.

It doesn't really work too well in the South Stand.  I think you have the same problems as HQ with the size of the stairways. 
I think that on the South Stand, the plan was to stop people during the first 5 minutes.
Where I sit, near the entrance, I have two options:
1. get upset by latecomers arriving and not knowing where their seats are and go through a process of standing up and sitting down every few minutes for the first 5 minutes or so of the game.
2. just stand up and clap when the team run out and remain standing for the first five minutes
-- I choose option 2.

For the Stoop, there are a few things that would help (I think).
1. Better signage at the entrances to the blocks.  E.g. block BC has two entrances.  I think that first timers do not understand the difference and can choose the wrong entrance.  It should say what seat numbers are at each entrance and whether they are on the right or left.   Also, we often get people with rows AA who do not realise that they need to go up the stairs from the entrance in row J rather than going down.  They are often quite grumpy when then walk all the way down to the front row then have to walk up 26 rows to their seat.  The steward would help - but there is only one steward for a lot of people.
2. Allowing front loading of the South stand for rows A to K.  That would cut the congestion on the stairs.

Well, that’s how it used to be many years ago, BUT, that was in the days when the bars were closed shortly before kick off and didn’t reopen until after the game had finished, so there was much less crowd movement during the play.
Personally, I prefer that approach, it seems to me that a lot of people seem intent on drinking as many pints as possible during a match, this necessitating the need to get rid of said fluid shortly afterwards, both of these causing disruption to those who only want to watch the game without a constant stream of traffic in both directions.
Unless the bar opening times are changed (which won’t happen because of lost revenue), then this is something we will have to put up with; limiting access to short periods of play while a stoppage is happening will not work, the returning spectators may well be refused access to their very expensive seats for fairly long periods at a time, the ground will gradually get emptier as more people head for the bars/toilets than are being readmitted.
The only solution to this is to only allow readmittance when a scrum is called, you usually have about 3/4 minutes before play resumes these days!!