If you have someone you know to be competent with the AMG C32/SLK32 tune you will be fine as its the same thing. TVT is a reputable vendor so if theres any doubts of your guy just use him.

The MB service facility can wipe out the tune if you dont bring it to their attention.

Most tuners will save your tune on backup and will be happy to put it right back for free. Confirm this with your tuner prior to purcahse.