To your question... no I have never taken an outcall, and I wouldnt if I was there for work
For me wandering through the RLD in Hamburg can be interesting enough. just before you get to Beatles platz, theres a massive big pink building with 'SEX HOUSE' emblazoned on the front.. this has several floors with multiple rooms on each, a bit like the Frankfurt RLD.. have seen some reasonable SP there. Its purely P&D with little connection if thats what your after... but you might be lucky.
Avoid at all costs doing anything other than looking in Herbertstrasse, thats the street with the walls blocking each end that has the windows on the street like Amsterdam... complete scam.. ask how much and you be told 50/100// then get in and thats just for getting in .. an extra 100 for HJ etc etc etc.. same deal with the nice looking girls near the McDonalds that approach you on the street.
I have only been to the 2 FKKs - Babylon over by the Docks (10 min taxi).. typical FKK but set up for the tourist so a little bit sharky.. The only place I'd recommend is Atmos FKK a few mins taxi (40euro) in nearby suburb of Harburg.. great welcoming place reasonable prices and good selection of girls to chill with. food and drink here is also good. Cant remember the entrance fee, something like 65 Euro.. for DFK/OWO/CIM mish & Doggy, I was knocking 150 per session