I would NOT recommend shooting +P ammo in any of the small Colt's made before 1950.
After 1950, I personally think the steel Detective Special would be fine with the "shoot standard .38's for practice, load +P's for business".
With the 1950 to the 1972 models this is a matter of personal preference, but most of the people who did this figured any accelerated wear on the gun would be the LAST thing they would need to worry about if they had to shoot the gun with +Ps'.
After the 1972 heavy, shrouded barrel Colt's were introduced, they were factory rated for limited amounts of +P ammo.
Here's a link to a late issue owner's manual with Colt's recommended +P ammo specs:
http://www.stevespages.com/page7b.htm
The pre-war Colt revolvers were noted for being a little "soft", and it was quite easy to spring the soft cylinder crane.
Due to this, I certainly would NOT fire ANY +P ammo in a pre-war Detective Special.