I bought an R89 head and paired it with a West Coast Shaving 78S handle. As mentioned it bumped the aggression up a small, but noticeable amount while maintaining that famous R89 smoothness. This combo can hang with any other razor I own.Considerations if you like the de89 and don't want an unknown quantity:
1) The Muhle r89 head is available seperately and identical to the de89 head except that it has a brass thread. It will be more durable than the de89 thread.
2) As you also need a handle, a cheap stainless handle will pair nicely with the r89 head and the extra weight just nudges up the aggression slightly. I have many razors. The r89 head on a stainless handle is still a staple in my den.
If you don't want to spend too much, you can get a Maggard V3 head (copy of the de89) on one of their own-brand stainless handles for just $25. That's value.