Justin Ford's page

Read and reread the spells. Have to agree with that detect thoughts is better:

The two disadvantages of detect thoughts I'd add (with the warm up time, range and being blocked by stone) are:

The chance (low) of being stunned
"If the highest Intelligence is 26 or higher (and at least 10 points higher than your own Intelligence score), you are stunned for 1 round and the spell ends."

The reduced DC (A spells DC is 10 + spell level + ability modifier)

Will forcing an alignment change improve the game you are running?

Personal ethics etc and the modern definition of evil are possibly irrelevant in your world and possibly not. In many classic DnD worlds like Dark Sun the Thief's act would be perfectly normal (non-evil) behaviour; however in a setting like say The Forgotten Realms it might constitute a more evil act by the dynamics inherent in the world. There have been so many definitions of Good vs Evil since DnD 1st edition that of course there is only one correct way to determine if an act is good or evil. The same question that a great DM/GM asks themselves for everything they create: "Will this improve the game I'm creating." My advice is that if you base your choice to force and alignment change (or not) on that premise (improve the game) rather than on the convoluted rules set out in the various rule books then you are sure the make the best choice. It is the difference, to my mind, between roll playing versus role playing.

EDIT Don't be sucked in by the whining of your players either! :P no one truly wants a blue ribbon for a race they never actually won!