Get both 3717 and this CD2006, you won't regret. It came to a point that I sold my 3717, lived without it for a couple of weeks and bought another piece.
The idea of movement service is good. Hope this watch will last you for years to come. To me, putting an ETA7750 on this watch is a worthy move. I wear this watch mainly as daily beaters.
+5 mins a day shows something is not right with this movement (which should be fixed after movement overhaul). No, it's not normal for unserviced out of box Asian 7750 hi beat to run 5 mins fast a day. Usually I got in the range of +10 to +20 secs a day for out of box Asian 7750 hi beat rate.