There is flashes available from AA, Dinan, and Mark D...
The main reason why the piggyback is popular is cost effectiveness. I am not saying anything about MarkD's tune so lets avoid a huge flame war. The point is convenience...lets look at this in terms of Pro's and Cons.
User switchable maps
Maps made for many different setups
Removable in under an hour
Not 'true' tuning from within the ECU program
ECU flash (Any company)
Not externally detectable
Safe tune, done through internal programming
You have to meet your tuner to revert to and from software (MAJOR convenience issue esp in emergency situations as we know even the local tuners sometimes aren't the easiest to get a hold of)
Tuned for one setup (can be costly if you do your mods in stages as I have many complaints of people who bought Dinan flashes)
Has to be installed by a tuner, cannot be done on your own
At the same time, you have to understand both products are great and cater to different types of clients, whether it is the individual looking for a good increase in power with stock like drive ability (our 135 is smooth as hell look at the graph) or the "flies around crap" crowd who are looking for a solution based on multiple needs.
I have yet to see an N54 car pushing more than 450rwhp on pump or race with an ECU tune. However, I may have missed something. Yes there are risks when using the piggy back units opposed to the ECU flashes but then again, this goes for anything - you mod your car with knowledge of what your getting int. You cant say an ECU tune capable of pushing that power will be safer because from what I've seen the engine wont take that for long. Ive seen N54 internals compared to others, and seen the results of high HP outputs run for a long time. On top of it, how much can those turbos actually push and handle for a long time? There's been many replacements already (we've done a few).
In conclusion, the ECU tunes are great and I also believe in ECU tuning - however the piggyback is the most cost effective solution for those seeking a solution that can cater to many needs, opposed to one.
On a side note, JB seems to be the most popular yes...however, one of the longest BMW tuner in this market is AA and they do have flashes for the ECU for a long time. However, at prices of $800+ for a flash PLUS a fee for each re-flash...it just doesnt make sense when you can buy all the tunes you can need for the same, if not less.
It all boils down to the customers needs, driving differences? Yes the ECU tune may control the boost smoother but in all reality it is not something most people notice. They AA tunes are done IN HOUSE and have been compared back to back with minimal differences the average user wouldn't notice.
Final statement: I am not saying anything about competitors, but some of you guys are clearly missing the point these companies are basing their products of.
Sorry guys not trying to make a speech but...I just like to be clear for all the people who don't know whats going on.