I've been running a pm for a few years now.Its works well for me and I have no regrets on its purchase.
I dont have a par meter but I did/do try to learn as much as I can prior to any purchases.From the t-5 lighting thread there was some par measures posted by grim and others.I believe par was not insanely high at the surface,I want to say between 400-45o's,but in the center,24" depth par was still hitting close to 300 ,and to the far sides 100-150.
Theres also an online publication whitch argues many if not most sps corals are nearing saturation for usable light at around 400 par.There were a few other persuavsive points that tipped the scale for me anyway.
I talked to pascal sometime back when he was switching his tank over from t-5 to halides and I maybe be entirely mistaken but I believe he said ,using a par meter the halides had way higher par from the surface down to below mid level.The t-5's seemed to have higher par on the sandbed. (I think)
If your considering a used fixture, the bulbs and reflectors both, depnding on age. reflectors if worn ,( mine have lost most of the silver coating) whitch is one key ingredient in reflecting light so well.
Reflectors are around 20$ a peice
bulbs around 20$ a peice ,just pointing out you maybe into it for 240$.