I would recommend sim4u in Berlin, did my JOC there in December. They use a FFS without legs at Lufthansa Flight Training at Schoenefelt in Berlin. Have flown the FFS aswell and you wount notice any difference in the dynamics or the stick.
The program is 10 hrs but if you would like 16 they will arrange that, my sim partner and I wanted to kill some time while waiting for our flights home so they arranged an instructor on 4 hrs notice for some additional hours, another ex-military German senior 737 captain with great teaching skills like the other instructors we had.
You will get thorough briefings and debriefings. In the sim you will do SID, STARS, HOMING, AIRWORK, and a bunch of T&G's, just what you'll do on your assesment one day. Prepare ahead with PMDG or an NG cockpit poster so you know some switches and they will introduce more advanced training as time might allow this.
Another thing I really enjoyed is that they book you into a nice hotel with their discounts next to the training center by the airport, so your stay is super effective. There is a nice kitchen at the hotel you can use and a supermarket next door, so you can make it a low-cost stay.
For me 4 hrs would not be enough, there is a big step from the flight school multi to the B738.