I was riding cardan-driven BMWs since 1999, but before always had chain-driven bikes. Since I made the plan & ordered the Esse, I rode a Yamaha TDM850 for some 4.500kms just to bridge the gap until the Esse was delivered - again a chain but w/o oiler.
Chain driven bikes are always kinda messy. Some friends have Scottoilers (quite common in Germany) installed; after some 100km for proper set-up they tend to be much less messy and the rim & framework is easier to clean.
A motorcycle chain anyway does not need lubrification as the grease for that is lifetime-enclosed between the O-Rings. The sprockets of cause do need lubrification. The grease is mainly for corrosion protection but since it is quite stick a lot of dirt is being collected. Both is sufficiently done by oil as well, however it tends to be less sticky and the oiler distributes it evenly over 1000's of kms.
I'm sure there are very good reasons for each and everyone here to stick with standard chain grease every few 100's km & cleaning when required. I just decided otherwise for this bike but I will observe closely. In case I am not happy and feel like this is not a good way of maintaining the chain drive, I will rip it off without any second thought. However the experience from my buddies show me that I might be *VERY* happy. Time will tell.
I only wanted to show how I realized it, not to start a discussion pro/con an oiler system. But, hey, this is a forum! Happy discussing!!