To quote Aaack Aardvark, did you know?
One of the traditional killer features of the Ruth2 family is that the feet are separate whereas they're firmly attached to all other bodies.
Now you may wonder how this can be a killer feature? Well, it makes adjusting the foot position much easier. You don't need a HUD, and you can save and recall the foot position with outfits.
Athena and all Athena spin-offs require you to open a HUD and change the foot position there, and you still have to go to the inventory to find and attach the "shoes" needed to adjust the height unless you keep them under your favourites. As the foot position is HUD-controlled, it cannot be saved with outfits unless you keep multiple copies of the same body with different foot positions. Not to mention that the HUD doesn't always work. As this is so uncomfortable and unreliable, most female avatars walk around on tip-toes permanently.
Also, Athena 5 only came with height-adjustment "shoes" for 10cm (4") heels. Athena 6 doesn't have any height-adjustment "shoes" at all anymore.
Ruth 2.0 and thereby also Ruth2 v4 have feet in three different positions plus corresponding toenails and, if needed, height-adjustment "shoes". If you want to change the foot position, just detach and attach feet, toenails and, if necessary, "shoes". Not only don't you need the HUD, but you can save the foot position together with the avatar height (by means of these "shoes") in outfits. So if you change from a casual outfit with sandals or sneakers to a more fancy outfit with heels, your avatar will automagically adjust her height but also the position of her feet. Just put on a different outfit. You can theoretically even do this in places where scripts are turned off.
And yes, I wrote "three positions". Flat, the tip-toe position for 10cm (4") heels that you see on almost every female avatar out there, and there are also feet plus "shoes" for 5cm (2") heels. And yes, they are useful. Another advantage of the Ruth2 family over Athena & Co. is that fitting rigged mesh shoes with 5cm (2") heels are available. They aren't as many as the countless Athena-rigged 10cm (4") heels, and they're currently only available from one maker in one grid, namely Dorena's World, but on the other hand, there are exactly zero Athena-rigged shoes with 5cm (2") heels to be found anywhere on the Hypergrid. You'd have to use a resizing script on Ruth2 shoes or try your luck at manually fitting old unrigged shoes.
To those of you who may now say that you'd rather stick with the HUD because that's what you're used to, and forcing you to replace your feet by taking the HUD away from you would suck: Ruth2 v4 has got foot positions on her HUD as well. And while Athena 6 has got three positions, two of which are useful and one useless, Ruth2 v4 has six (!) positions, four of which are useful and two useless. Apart from the positions for flat shoes and two heights of heels, there's also a specific one for going barefoot. You can only adjust Ruth2 v4's flat feet, though, not the raised ones.
Oh, and Ruth2 v4 doesn't need to wear the "broken ankle" fix because it's already built in. You can toggle ankle lock on the HUD if you have to.