Well, good news and not so good news.
When I replaced my ConvaTec pouch with the Hollister pouch yesterday, it seemed to snap on OK. No leaks, no problems. However, I woke up this morning and noticed that I had a very slight leak over night. Only my t-shirt was a little damp. So...maybe they will fit together, but not so well. Maybe since I was in a horizontal position when sleeping, the urine pooled a bit more around the flange.
So to do a little more investigation, I took out a new ConvaTec flange and a new Hollister pouch and just tried to just put them together. There is definitely not a good fit. I could not get the Hollister pouch to fit onto the ConvaTec flange completely. Though they are both '57mm', the manufacturing of the actual plastic grooves must be a bit different. And, the ConvaTec flange was probably a bit warm being next to my body so it might have been able to 'stretch' a bit to accept the Hollister pouch.
The unfortunate thing is that Hollister does not make a similar moldable flange. It does have a somewhat similar 'FormaFlex Skin Barrier' flange, but it did not get a good review back in 2016, by Vegan Ostomy.
But, I'll have to see if I can get some samples of the 'Hollister FormaFlex Skin Barrier' flanges to see how they work. I've had my ConvaTec on for up to 7 days with no problems. Hopefully, the Hollister will do the same. I like the ConvaTec pouch except for the bulky tap; it pokes out through the pants, espcially as the pouch fills up.
Anyone have an opinion of the 'Hollister FormaFlex Skin Barrier' flange?
PS Found an 'updated 2021' review by Vegan Ostomy but really the same video. But it has a few comments at the bottom.