Hi, ski bum - the only gastro related problem I had with the oral bisphosphonates was heartburn. For whatever reason, after my ileostomy surgery, I could not tolerate the oral meds at all. It was at that time that I switched to the Boniva infusions to avoid the gastric route.
For the osteoporosis, I also take over-the-counter calcium, Rx vitamin D (50,000 IU weekly) and Calcitriol (another form of vitamin D).
Just to add - I did express my concerns to my dr. about the risk of fractures with the bisphosphonate use long term. That is when he/we came up with the 5 year plan.
Since every situation is unique, I think it's great that you're being proactive in researching your options. Best of luck to you .