Has anyone tried this, is this a fellow STM'er?
Link - http://www.warriorforum.com/warrior-...time-only.html
Can anyone vouch for it or should it be avoided?
Yes - the owner is a fellow STM'er. See the thread here:
http://stmforum.com/forum/showthread...t=mobile+scout
Note the $30 off discount code in the first post. 
I can personally vouch for it as I've been a subscriber for over a month now. You can sort landers by the number of days seen, country, operating system, and traffic source. For any specific lander, it will tell you data such as which traffic sources it's running at, the geo(s), operating system, and other landers that are found on the same domain.
I still do spying the good old fashioned way - by making a list of publishers of PPV networks and manually browsing to them to trigger pop landers. But mobile ad scout saves a lot of time and gives me a bird's eye view on what lander types are being used the most often - an indication that they're converting well (which you won't know for sure until you actually test them! But the more often you see a lander type, the higher the probability that they're making money for people.)
Amy
Ahh ok, thought it must be someone on STM
Thanks for the review, I think I will be checking this out in the next few days....