From what I've read, I'd say the opposite.
It gives great accessibility on devices supporting it (and
yes Firefox mobile has support for the tel type) without any
drawbacks anywhere else since it fallbacks to a simple text
fields on all browsers without explicit support.
Plus it seems to be part of the HTML5 specification at W3C:
Moving Dolibarr to full HTML5 compliance is a huge
undertaking but I can see the benefits for all our users.
inline-block is part of CSS2 so it should be safe to use
without any restriction.
My 2 cents