Having two 2008 335xi that I have tracked, worked on, tweaked with coded (with NCS Expert and Carly), here are my opinions based on my limited experience:
The "orange/half engine symbol" without limp mode, mentioned by DieselDrink is often the 30FF or 30FE code indicating Turbo under or over boost. I had it on both 335xi and in each case the dealer fixed it for around $250 by finding and replacing various vacuum lines. Short accelerations are not going to overheat anything.
The real limp mode many are experiencing without codes are due to high coolant temperature. What idiot designer removed the coolant temp gauge from these cars? Perhaps the same idiot that removed the oil dipstick.
Using something like the JB4 or adding a real gauge is the best way to monitor coolant temperature.
Ever since removing the lower plastic engine under-cover and the metal "tray" over the back of the engine, I have never had a limp mode at the track and the oil temp stays below 250 (with OEM cooler). That tray can be removed in less than 5 minutes using only a 8mm nut driver. Makes the engine sound better too.
You really need something like the Carly scanner to read all the BMW specific codes; a generic OBD scanner is nearly useless.