Mmm... I have found that Genesis 1 also takes the M3/V3 poses very nicely as well. Some minor tweaks on the hands/fingers and feet, but those really are minor usually.
IK I never fully understood. I just know that because my poses frequently put the figures into some extreme bends, that more often than not I have to turn off the IK in Poser for the poses to work properly. And I frequently have to turn off the limits on the figure in Studio as well for the same reason.
The IK in Poser is supposed to assist in realistic positioning of the legs...it's handy to grab the hip of the character with IK on and squash or turn the figure, and watch what happens to the legs. I'm sure there are other uses. Otherwise, almost all of my poses involve "feet off the floor" poses, so it just doesn't help me.
Thanks for the tip about M3 and Genesis....I could begin my poses in M3, then transfer for tweaking in Genesis. That decides it, if M3 works well with Genesis, I'll begin with doing a M3 Last Supper set, and knock out two figures at one time while doing it...good tip!
Here's how I like to think of IK, it's more how you as a person think about your own movement. If you see a cup, you don't think, okay body, lets move the collar, then the shoulder, then the forearm, now lets twist the hand and almost there. . . .
No you pretty much see the cup and decide to grab it with your hand, even through really your body is figuring out how to move those muscles. I use IK all the time, and you don't have to use it just when your figure is on the floor. For instance, lets say Dawn or Dusk is riding Harry, but there foot isn't quite making it into the stirrup. If you turn on IK for the offending foot, you can dial in it's X, Y, and Z translation, and the rest of the lower body will follow. So in a sense the Hip always has IK on.
Also I use IK if I want a pose with both hands touching, or to touch a certain part of an object, when moving the object doesn't make sense (if I wanted the hand to rest on the back of a chair, instead of making the chair 'float' off the ground by raising it's Y translation I would turn on IK on the hand, and lower it's Y translation.
Of course there are lots of times when IK is not the way to go, and it does interfere with lots of other things, so you usually have to turn it off once the posing is done. But it can be a huge help in posing a figure.
