I subscribe to the same opinion that
does: JB4s and other so-called 'piggyback' tunes are a relatively easy way to coax more power out of an engine -- but that ease is at both the significant risk and the sacrifice of a number of things that you absolutely cannot control without significant additional expense (and you may as well get an ECU tune at that point of expense).
The point he made about BMWs is a fantastic one. It literally took years
for large aftermarket shops to crack the ECU on BMW's Nxx engines, particularly the N55. That, as well as relative cost, is why piggyback modules became popular for BMWs.
However, for our cars, the ECU was cracked first, then
piggyback modules became available. What that tells me is that tuner companies such as Burger (which makes the JB4) believe that there are enough people who can't stomach either/both the cost and relative inconvenience of a true ECU tune to support bringing a piggyback device to market -- ergo, the market force for the product is not extra power: it's cost. IOW, a piggyback is a 'cheap' way to add it on a car that already has a better way available.
So basically, a piggyback device on a Porsche is like listening to a McIntosh audio system through Realistic (Radio Shack) loudspeakers. C'mon. This is a Porsche. Don't cheap out on it.
Also: Because of the way a piggyback module works (it basically fools the existing ECU into delivering more this-and-that), things like your boost gauge, various temperature gauges, and other key ECU monitoring circuits -- basically, anything controlled by CAN-BUS that the JB4 attaches to -- will cease to be accurate. Do you really want to risk that?