Heists are more efficient than conversion...technically.
So, 1 key or Information costs 5 casing, and with a gang of hoodlums, 5 casing is worth 1.4 actions. Each card that consumes one key or information costs 2.4 actions, and on average, cards give you 2 making waves per action (in well-guarded, where Burglar's Progress is worth 3 mw cp). Now, the effect of the immediate cost of 10 casing technically approaches 0 the longer your heist is. So heists, should they go long enough, are worth 2 mwcp/a. However, as most people want less than around 12 making waves, this is worthless.
Also, you will eventually die to the sleeping dogs card no longer how much advantage you have. Perilous may honestly be better; you can circumvent the sleeping...dogs? with skills.