My personal (very limited) experience with female soldiers, were not the greatest. I do try to keep an open mind as my experiences was not in an lengthy day to day situations.
While teaching with SARG, most (as in high 90%) were terrible at basic level soldier skills. Example being zero/qualifying with a weapon, if I was on a range late it was generally b/c of a female soldier or an older officer (I'm talking NG-USAR old). Same level of training, more intensive coaching and a lot of calm down its not worth crying over motivational conversations. However, I've also had some really awesome female soldiers who took in the training and performed as well as some of the best males, again few and far between. Another example was integration of female instructor's, we had to train up a lot of them to take over for us. It was a chore and I did get butthurt on some of the bullshit. Like, its time to prep a range, all the sudden females soldier couldn't be found, never carrying their share of the equipment, constant getting out of work b/c they need to square something else away, pay, etc. At the time I was pretty bent about it, but didn't have the rank or position to change it.
Another was my last deployment, we had female soldiers and a lot of support soldier filling roles for the convoy security mission. A lot of the same stuff, can't meet the basic female standards for PT, getting out of PT b/c XYZ bullshit excuses, pretty much a complete lack of wanting to do the job. I can't even count the amount of time wasted b/c of it. That said there were a few, as in two, female soldiers who were locked on and I had no problem working with for that particular mission.
Finally I will state that my experiences with female SRNCO/OFFICERS has been a mixed bag. By the same could be said for the males. However, I cannot recall one single female NCO or Officer, that I said damn, i want to work for her, she has her shit together, good leader, etc.
Now my personal opinions are one standard, meet it, if you do you have the job, if not, see you later, and that's for male or female. As for having a infantry squad with 2-3 female soldiers in it, patrolling the badlands. Probably not based on my past dealing's, they would need to be exactly like the guys, at not bring a bag of issues or a get out of hard work attitude. They're out there, but from my experience, few and far between.
As for Ranger school, no dog in that fight. Outside of a congrats for earning their tab based on the standards RTB required them to meet, whatever they may have been. The dudes next to them would have flipped if they were getting special treatment, especially the ones getting dropped or recycled. So I think it's safe to say they met the same standards as the males in that class. I think the more important issue is the operational training and development of units, effectiveness the same, up or down? Unfortunately, the only way to find out at this point, is to test it and let the cards fall where they may.
My $.02