@Matthew Perry, thanks for the comment.
The reason I started investing with these was for diversified investment income through the dividends they pay. I am not counting on appreciation for any of this even though I include it in the IRR calculations above which I know may not be the correct way... It is (feels like) a short term option to invest low amount of money and get a foot in the "real estate" field (sort of). I told myself that if the yields stay around 7 or 8% then that works for me. Time will tell but again, diversification is the main point for me. All these combined represent only about 5% of my portfolio.
All the advertised yields for these investments are advertised between 6 and 10% and it is what I see so far. These have been going at these rates for over 2 years, steadily increasing for most of them. Given it's not a very long time but as far as the business model is concerned, it seems sound and sustainable for me. What could change are terms and management fees which could dampen the yields. We will see if/when that comes.
Not sure how you calculated the "3.5% growth in a month" figure. For Fundrise, it went from 11.5% to 12.95% for the average of the two funds for 2018 so far, including appreciation (change in NAV). The increase was mostly driven by a change in NAV. The dividend yield has not changed at about 8% for the income fund and about 6% for the growth fund.
I am now investigating more tradition SFH buy and hold for rental but I am just looking at some of the deal on Roofstock to get a better idea of what makes sense. It's only been a few days since I've started to look at Roofstock (~100k sale price) but the deals I saw so far seem to net only about $100 per month. It's not all that bad I guess but that's just about the same I would get in dividends by putting $20k into Fundrise or other of these syndication (Groundfloor is my preferred place at this point).
Got to think about how tax, depreciation, etc. play into this but as a first pass, not sure what to think about the added headache that may come with remotely investing in SFH. Again diversification is an added benefit to that.