Anyone who complains about tech support or any other support from Diezel has obviously NOT dealt with Peter at all and is full of it.
I have owned 2 Diezel amps (and still own one) and any issues I have had (minor ones, and modding) Peter has been very helpful, sending me diagrams and pictures, and replacement parts, no charge, all the way from Germany, and I have bought my amps 2nd hand.
If I had a problem with a Marshall, I've been screwed and have had to spend hundreds of dollars to fix those amps. Mesa usually fixes their problems, but fights you all the way even down to the tubes you are using.
There is NO other company out there that has better personal service than Peter Diezel.
Does he need more presence in the USA? yes. But Don't anyone ever say anything bad about the service being provided personally by him, as it is nothing but amazingly good!