I've practiced both ways and shoot equally bad either way.
The stance is the foundation of shooting, and SOOOO many shooters try to build a house on a poor foundation, which never works out very well...
Check out this muldoon..
First shot, maybe on target, follow up shots = crap/slow due to poor stance that does NOT facilitate recoil management.
How about these folks...
What you SHOULD be seeing in the photo are the instructor types lovingly placing a boot in the keister of all those shooters standing straight up like a post, or standing with their feet too close together...
While there are pro's and cons to each of the contemporary stances taught today, they ALL share some common characteristics...
1. The feet should be spread far enough apart to provide balance and stability.
2. The knees should be flexed for balance, comfort, and to facilitate recoil management.
3. Weight should be forward to facilitate recoil management.
4. The stance should be comfortable and provide an all around stable shooting platform.
Whether you use isoscelese, modified iso, or weaver, if your stance doesn't have these characteristics, you're doing something wrong.
Check out "the great one"...
Arguably THE greatest competitive action shooter in.....well...EVER.
While most competition shooters use some form of the iso stance, you will see that they all incorporate the same characteristics listed above.
I treat the stance similar to how I would treat a tackle in football. If I try to make a tackle from a position of poor balance, stability, and with my weight back instead of forward, then I am going to get knocked right on my keister. Recoil is similar, and while it won't necessarily knock you on your tail, it is far easier to manage with a good aggressive stance, and it is easier to transition from shooting to "hands on" should things go...not so well.
Here's a couple of nice aggressive stances....casual, but still aggressive...
Note how they share similar characteristics as the stance used by this muldoon...
Best of luck