With TOU service you charge it at night for 5-7c/kw and use it during the day to arbitrage the price difference. 

As far as ethically that is part of my nature and I don't care for the aggressive (potentially predatory) strategies discussed by others, but I see value in offering a transparent and convenient service with lower costs and faster turnarounds than traditional MLS transactions. 

Therefore right now I'm considering using a service for submetering and then billing separately (currently I live in the ADU and rent out the main house).Does anyone have experience with this? 

I hope you are asking two separate unrelated questions, because there's no point in doing cost segregation for properties held inside your self-directed solo 401k, save for some very rare exceptions.Some of the Bigger Pockets experts who operate reputable costs segregation companies are @Bernard Reisz, @Yonah Weiss and @Julio GonzalezSome of the Bigger Pockets experts who offer Solo 401k administrator services are @Dmitriy Fomichenko, again @Bernard Reisz and @Brian EastmanReach out to them and see if they can help.

.: I would only buy single family homes in the best locations I could afford rather than messing with multifamily and less great locations, and I would use my local credit union for loans because they keep them in-house and service them in-house, so that I wouldn’t have to deal with loans being passed around among all the sketchy loan servicing companies.  

turnkey is just a bundle of services. 

Pure client service.  

In real life, the portion that goes to principal increases by the same amount that the interest due decreases.Credentials don't seem to matter in this thread, so I won't mention the MBA I have with a specialization in finance, or my time spent as a commercial real estate loan servicer.  

A local lender can be helpful since they often understand the market better and may offer more personalized service, but it’s not always necessary if the terms are great. 

Their customer service is great.