I have a 250 engine in my 230, as the original engine rotted out (PO left it outside for years unused). I liked the fact that there were more main bearings than the 230, yet did not have the 'thin' cylinder walls of the 280. I've seen many posts on this board touting the relative benefits and drawbacks of each of the engines, and I have seen no clear winner.
If you have a concours show car, then no doubt you will be driven to install a 230 engine, but it will no longer have matching numbers (if that is relevant on the SLs). Perhaps there will be some impact on resale, having a 250 rather than a 230 in your car, but I am not sure that would be important unless the car is original in almost all respects. I have a driver, and am very happy with the 250 engine.....
Regards -- Roger
1966 230SL