Market Samurai VS Link-Assistant Rank Tracker

There has been talk that MS has been inaccurate with it's rank tracker so I just downloaded MS and Link-assistant/rank tracker free version and checked 5 keywords to see the accuracy of both. Here are the results:

All of these keywords were checked for ranking in Google

1- Out of 5 keywords I checked, Market Samurai was off an average of 10 positions so if a keyword actually ranked in the #50 spot in Google, MS would say it was #40

2- Out of the same 5 keywords I checked, Link-Assistant/ranktracker free version was off an average of 2 positions, so if a keyword was actually in spot # 50 on Google Link Assistant would say it was on #52.

MARKET SAMURAI- I think I might know why MS was off so much. I believe MS is counting 10 search results per page but I don't believe it is counting the Google Maps listing in the 10 positions. The keywords that I checked all had 7 Google Maps positions on their 1st page of rankings so that would account for 7 positions being off.

Also, in a few pages Google added a video link in the results making those particular pages have 11 or 12 positions instead of the 10. So if MS isn't counting Google Maps listings into their results and the extra video links then this would account for why MS said that my keywords were ranked in the #40 spot instead where they are in the #50 spot.

LINK-ASSISTANT/RANKTRACKER FREE VERSION- I think LA did count the Google Maps listing in their calculations but I think they were off an average of 2 spots is because on a couple of pages in each keyword, Google added video link(s) making that particular page show 11 or 12 results instead of the 10 it would normally have.

I hope I made sense here.

PS. this little web based script was dead accurate for every keyword. I don't know if it tracks your IP or not but it works.
What Page of Google Am I On?