I'm sorry for all you have been going through. I also have a sliding haital hernia, by the way. Makes it possible to eat well some days and some other days, I can't get anything down. Since you had a hernia before the sleeve and it is back now, if repaired again without converting to the bypass, according to my surgery, the hernia will likely return in 3-5 years, unless your diaphragm is supported with a mesh filter. Making the decision to have any WLS is difficult enough, let alone having to decide on a revision. It really comes down to quality of life, from what I've experienced and heard in support group for months now. If you feel you can manage your reflux well enough with medication, then maybe surgery is not worth the risk but acid reflux could lead to other things down the line... In my case, there is a plethora of reasons for revision, so that in a way, has made it easier to decide (scheduled for 9/9/19). Also, regarding your main concern (dumping), I actually have that now with the sleeve (maybe 3-4 times a month). It happens when I make poor choices (high sugar or high fat). Yes, it's more likely to happen with the bypass, but I think managing our intake regardless of surgery type is key to preventing uncomfortable dumping situations.
I'll have surgery just 10 days before you, so if you'd like, let's keep in touch and I'll let you know how it goes! I am most likely to have an open surgery (surgeon will try laparoscopic first) due to an obstruction in my sleeve, ulcers, and scar tissue buildup being 7+ years out, so my recovery may be a bit different/lengthy.