You need Platoon for Pit so it hardly arrives earlier.
It's about a minute faster due to the reduced manpower cost and double building with IS, but with a rush build you can get it reaaallly fast. (Could always rush it, it's just more effective than ever) Can get it in 2 minutes with the fastest possible build.
I wouldn't say it's broken or anything, it has it's strengths and weaknesses like any other strat.
Of course, doing this can really fail miserably because all they have to do is spend that extra manpower and attack you in the minimum range.