It stops spine from rounding, but does it place too much pressure on SI joint?
Yes it's safe
Yes its safe....
Yes it's safe.
Hope so! I do it all the time.
It's also better for your lower back. Stuart McGill, an expert on the spine, states if you use the leg press, do one leg at a time
I've been doing this exercise for quite a while and I love it. I have found that it actually has helped even out my leg strength. If you are a little reserved on it, try incorporating Bands with the exercise. I believe John Meadows has an article about them.