Look around the other topics on this, but the short answer is much more than the clutch mod, and probably much safer for the engine, as to who does the best flash I think the jury is out, but the ECU-U is probably the most common and folks seem very happy.
A proper ECU flash can be much better than the CJM. The CJM, while effective, has some drawbacks. ECU flashing has the ability to be tailored to the customer quite a bit. No matter which flash you choose, ECU flashing is the best bang for the buck performance wise for the Tenere.
^^^ +1 I've tried both, as well as many others. CJM first, then the ECU Unleashed flash. Don't for a minute think they are the same. The difference for me was massive between the two. I personally never thought much of the CJM. The reflash is the best $450 you can spend for a performance upgrade.
I've had the opportunity to work on 100 + Tenere's.. The ECU work is much more than the clutch jumper....... Lots of info out on the forum about both and comparing and talking about each set up.
I ordered a reflash from OTR - the ECU is on its way back from Germany.
Will report back after installation. Very good support from OTR - theyanswers e-mails at once.