BMW seem to have had various front and rear spring rates on the various models and years.
My urban had a harder front spring and softer rear spring than was ideal for my weight.
Most suspension experts suggest you measure your springs 'rider on sag' both front and rear to give you an idea if your bike is oversprung or undersprung. This is fairly easy to do.
At the front use a tape measure down the slider to two points. Measure on a stand unloaded and then you measure with you mounted in riding position feet up bike on ground. The difference needs to be around 40mm.
Rear suspension, do the same from the axle to seat and this needs to be around/under 40mm. Just check what spring preload is on the rear shock, ie how far the spring threaded collars at the top are wound in. Should be about 10mm preload from factory to give you 35 mm ish rider on sag.
If your front sag is more than 40mm you need stronger springs or try an increase preload with a spacer in fork.
Same at rear, if you have to wind the preload to 0mm to get 35mm sag you need a softer spring. More than 20mm rear shock preload and you need a stiffer spring.
Replacement springs are fairly cheap either end.
The Rninet conventional front suspension damper rod forks usually have way too much high speed compression damping that causes harshness.
You can only fix that with new internals somehow. Racetech 36mm Cartridge emulators are simple and cheaper than replacement inserts from ohlins, ktech or andreani which are available for ÂŁ500 and above.
You can also adjust fork oil level to increase/decrease fork dive when braking hard. My Urban had way too much fork oil level from the factory.
Finally the standard rear shock is also rubbish for high speed damping, but this can only be cured by an ohlins, wilbers, Racetech, ktech, nitron, mshock, YSS, Matris replacement.... Id solve the other issues above first before buying a new shock.
I replaced fork springs and shock springs, then fork cartridge emulators (I bought YSS 36mm ones), then reduced oil fork level and got to a reasonable comfortable good handling bike. It was awful stock.
I then bought a Nitron R2 rear shock using same springs, but this didn't give me as much improvement as the first mods, but still worth doing as they are so nicely made and have a better ride quality, just least bang for your buck.