That's a very good question. For me, it is worthed. I drive 60k km a year, so I almost live in my car. Every cent spend an on my car is tought over very well and I enjoy every investment.
End of this year, the new JTD 16v engines of Alfa come out, with about 136 hp ex-factory. I guess they will not be EUR 900 more expensive then the existing 115 hp. So economically, I do not think it worthed.
Today I raced a Passat T-red D- red I (130 hp?). Man, I loved showing him my back. This moment (for me) was worthed EUR 50,= alone. I hope to have many more of these moments...
What I notice is a lot more punch between 2k and 3k revs, especially in 4th and 5th gear. When driving on the highway, this means you can play a lot between 90 and 150 km/h. The car has become much more responsive and quicker.
I had a Seat Cordoba TDi 110 hp before this, and in the beginning the Alfa (I thought) had less punch. In reality, the 147 is faster, but more smooth, so it feels less powerfull.
I guess if you have a towing hook, you have even more use of it.
You cannot re-sell the chip (because it's remapped), the 900 EUR for me means that I have to depreciate it in 3 years.
In short: it's a matter of heart over head. For me, it was worth it. But in absolute figures, I guess it is a lot of money.
Björn, I do not know what you have now (Golf TDi) and what you're looking for?