A small 2-4 multifamily, an appraiser might use a blended approach, and use some weighted average: 80% comps and 20% income, for example. 

It's a blend of facts and my own semi-experienced opinion.   

@Giovanny Garcia you should also switch to blended retirement.

I blend in pretty well.

I like to look at it as a per door compared to blended rents per door. 

National credit tenant, 20 yr leases, 1.5% annual rent increases, 6 additional 5-yr extension options, blended cap rates over the 20 yrs in the 7.5 range. 

I'll probably have a blended cost of money around 5%.Your warning points A -E are a good checklist, and I have a decent mitigation for some:A. 50%: I'm considering managing them myself (I already manage 7 properties while working full time) but in case I'm not able to handle the volume I've built into the expenses 10% for professional management and through my network I'll work hard to find a reputable company with good references.B.

., target retirement date) that provides a blend of stock and bond returns.

If a real estate investor conducts activities that were popular 5 and ten years ago in blending installment contracts, most likely they are in violation of law.

They did the opposite of take risks with customer's money and had a unique blend of customers.