Hello Dan & All,
I agree with Dave & Peter and wouldn't recommend this method.  Because Dan
requeens each year and keeps one year old queens that's the main reason he
sees little or no swarming.   There are many methods of keeping bees and I
have heard most at bee meetings including the excluder to stop swarming
method.   I also do not believe and practice clipping wings to preventing
swarms method.   Both methods as Peter says do not address the real causes
of swarming.   Clipping wings in my opinion could lose a valuable queen in
the grass and a excluder on the main entrace would cause congestion. Also
like  Dan has said most virgins can go through a excluder anyway. Because
Bee-L is a discussion you get all sides to a beekeeping issue. If YOU want
to use a excluder and clip wings to prevent swarming I see those as not huge
drawbacks to your beekeeping .  Maybe not drawbacks at all.  I have tried
both methods and was not satisfied with the results in my area of the U.S.
Sincerely,
Bob Harrison
Odessa ,Missouri