I have found no record of him online aside from self-published articles made to make them seem more reputable than they are.  

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 appreciate any advice on whether it's a good idea to invest in land on a slope and the potential challenges of building on such terrain.If this seems like a worthwhile investment, can anyone recommend reputable construction companies that specialize in cabin builds on slopes? 

With that said can anyone suggest reputable lenders that are able to assist me with a debt consolidation loan of ~25K?  

Start to see what makes one more than the other you might have one site looking at quartz counter tops with huge living rooms and the other looking at plastic counter tops,  being able to identify this will help you identify where your property could sit.  

They either had below mkt. rents or high vacancies and bad reputations and with super managing them I significantly grew the cash flow. 

I know it can depend on factors like the borrower’s credit, payment history, and loan terms, but I’m looking for general guidance or ballpark percentages based on your experience.Top Buyers/Companies:Who do you recommend as reputable buyers for these types of notes?

If the company is reputable, I don't need to vet the company.

I am experiencing the same issue and I have professional photos, using a reputable real estate broker, and in a very rental friendly market.

We wouldn't advocate for them otherwise as reputation is everything in this business.