Mature Source contains the same content as Mature Women. You're getting a large collection of material with babes in their 30s (young, but they could still be MILFs), 40s, 50s and 60 (entering GILF territory).
As is the case with MatureWomen the content on MatureSource comes from the "channels" section where you'll find 405 videos and 436 photo galleries from 10 sites, including MILFs Exposed, Sexy Cougars, Cougar Sex Club, Bang My Stepmom and My MILF Boss. The last update was a few weeks ago to that last one I listed, but the others are either rotating their content or not updating at all.
I like that whether you check out the scenes with women in their 60s or go for some of the MILFs who are a few decades younger than that, you're getting loads of intense action. You'll see lesbian strapon sex, loads of older babes being banged by younger studs, lots of threesomes and an entire site dedicated to foursomes where one man takes on three cougars.
The site also has a "videos" section that's automatically filtered for "mature." There you'll get over 1,000 extra scenes taken from nonexclusive DVDs. If you click on "featured" you'll see most of the movies from the channels. There's also a MILF tag for even more scenes.
The site also has a "pictures" section that has another 495 galleries (not overlapping with the channels at all) that fit the theme. So this website is positively teeming with older hotties getting naughty. You can count on seeing both older pornstars, like Nina Hartley, and amateurs.
With so much theme-related content you may worry that it will be hard to keep track of what you like, but you can save your favorites. You can also rate the scenes and sort by the rating your fellow surfers have given. You can also leave comments, so the only thing missing is an advanced search. At least there's a basic one as well as keyword tags on all the content.
However, you'll also find tons of other content and sites through the other networks that you can access with your membership, including Mega Site Pass. They cover a myriad of niches, so for many of you they may be merely the icing on the cake. At any rate, Mature Source seems worth your time and money even without taking the bonuses into consideration.