I made up my mind and ditched the idea of using Amplitube. After reading about and testing a Line6 M9 and M13 I chose to go with a Line6 HD500 even though it is not meant for bassist.
The main reasons for that are the Dual Channel ability and the price. Dual Channel means I can apply dirt on one side and keep my signal clean on the other. Sum them both and get distortion sound without losing bass and intelligibility. As for the price it is almost the same than the M13 but the HD500 is much, much more flexible in it's signal chain. In bonus you can edit your tone with Line6 Software in a computer wich is a nice graphical way of doing things.
Thanks for your suggestions.