I am on MR and do not take casual words like oh mine is at 17x mine is at 18x, it varies from users to users. Being with MR for so long and being extremely sensitive to latency changes, I can tell you the upstream that MR uses are.. mehh..
And if you look through the thread enough, you have to factor in the chances of you falling into the category of users having really bad latency. Anyone can paint you a good picture or tell you words you wanna hear but at the end of the day you need to do your own research and weigh in all the pros and cons of a particular ISP you want.
I wouldn't claim have tested all the games out there already but I have certainly played a fair share of games since I joined MR. Dota, League of Legend (US/SG/TW), Heroes of Kingdom, Guildwars2, Tera US/TW, C9, Path of Exile, Diablo 3, Dragon Nest, Dragon Prophet, World of Tanks, Call Of Duty, Battlefield 4, Dayz Standalone, Arma 2, Arma 3, Archeage, APB.
I don't have bad experience for ALL of them but I wouldn't say the experience is the best for a plan that is advertised as 'custom routing and catered purely for gamers".. gimmicks I'd say.
Being on MR I'm supposed to sing their praise and tell you to give them a chance but it would have been against my conscience to do it when in reality they are not doing so well.
Personal experience, VQ(especially with the new dedicated pipes they have to the US) and Singnet both have better and more consistent ping for gaming.
PS: Yes I am on Gamer plan fyi.