Nothing spectacular - simply going for Teammachine slr with 105, stripping the groupset and selling it, replacing with ultegra + some aero wheels is way better than buying Di2 version. Buying Di2 and wheels is also a little over the price of Di2 version of a bike. The difference between models is only groupset and the wheels. BMC provides you fairly cheap and primitive set of wheels with every model. Groupset is usually a little bit cheaper with the bike but not in the case of BMC 
And framesets from BMC are SLR01 so more expensive than whole SLR bike and the difference is not worth it in my opinion.
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