Much of the material I have read provides testimony of people who have many more than 15 houses with no problems.

This is the short answer why this year Venmo, et al has a $600 limit now (granted, the congressional testimony is so that Feds can catch rich people).All this being said, I think any cpa/accountant will have you file a 1099. 

Nevertheless, the courts have also stated that it was not required to accept a post-event ballpark guestimate or the unverified, undocumented testimony of taxpayers.

Jose SalazarHow strange - literally on their front page they have a testimonial from someone saying they can manager their property seamlessly while in Tanzania.

Reviews or testimonials 

Like you I am skeptical and want to hear some first hand experience, not just "testimonials". as Tom mentioned, their website has grammatical errors, many many grammatical errors which is a red flag.

Your website isn't really working unless you go to the unsecured version; may I suggest that you want the testimonial to be more formal. 

Do you want a testimonial so future renters can see you've gone above and beyond expectations in some way?

The court first noted that a taxpayer may establish hours of participation in a real property trade or business by any reasonable means.18 The court further stated that this does not require contemporaneous daily reports and that reasonable means includes “appointment books, calendars, or narrative summaries” that identify the services performed and “the approximate number of hours spent performing such services.”Nevertheless, the court also stated that it was not required to accept a postevent ballpark guestimate or the unverified, undocumented testimony of taxpayers.Note: The court also did not count any hours for seminars because it found the taxpayers did not present evidence to show how the seminars related to the residential rental activities

I have worked my *** off for little money in the past, but it has almost always paid big dividends in the form of future business, referrals, and testimonies as to my commitment.