Being a fan of [name]Bridge[/name] to Terabithia I really liked [name]May[/name] belle, I would never name my daughter that though, however I wondered do you think [name]May[/name] belle out-shines [name]Mabel[/name] or are they equally bad? Since I am from Australia we pronounce [name]Mabel[/name] almost like [name]May[/name]-bull so I prefer the sound of it, what do you think?
I like [name]Mable[/name], I like [name]May[/name], I like [name]Belle[/name] but I don’t like [name]May[/name] [name]Belle[/name] as a full name. 
You may like [name]Maribelle[/name].
I love [name]Mable[/name]. I also love [name]Belle[/name]! I think [name]May[/name] [name]Belle[/name] works for a first/middle combo, but not for a full first name. I like the suggestion of [name]Maribelle[/name]. Beautiful.
[name]May[/name] [name]Belle[/name] is cute! I never liked [name]Mabel[/name], because it sounded so frumpy and farmer-girl. But [name]May[/name] [name]Belle[/name] is adorable. I also rather like Mabeline.
I never could see the appeal of [name]Mabel[/name], personally, so I think [name]May[/name] [name]Belle[/name] could be a sweet alternative! It’s still a bit too close to [name]Mabel[/name] for me personally, so I wouldn’t use it, but it’s nice for someone else.
I am from the States and we pretty much pronounce [name]Mable[/name] the same way as you, kind of rhymes with [name]Maple[/name]. That said, [name]May[/name] [name]Belle[/name] just sounds like someone slowly enunciating [name]Mable[/name] to me. I like [name]Mable[/name], but not so much [name]May[/name] [name]Belle[/name]. Too choppy.
My great aunt was name [name]Mae[/name] [name]Belle[/name] I think it is querky and fun but I do know that she HATED [name]Mabel[/name] and HATED when people pronounced her name that way. Might be an issue. She went by Mabe but I think you could do [name]Mae[/name] obviously. I have thought to use it but it feels a little forced to make that separation so it doesn’t sound like [name]Mabel[/name]. I do like Mabe though.