How "valid" is to use a term marked as "unstable" for a data publisher/consumer?

Hi all, 

[ Apologize if this question has been answered before in this group. ] 

Recently, I was working on a project where we were just reusing existing terms for building a knowledge base for a private company. When we were considering using for example foaf:birthday, I was told by someone that it was marked “unstable” in the vocabulary file. The normal reaction would have been “so what?” ;)

However I found the question somehow interesting in the sense that the vocab defining the term status of the vocabulary [1] uses“unstable” for all the properties in the vocabulary, and of course it is reused by many vocabularies [2]. At the meantime, FOAF is one of the most popular vocabulary used in the LOD cloud (stats for 2014 here [3] ) and I guess there are many data modeled with some of the terms flagged as “unstable”. I found an example dataset here for Nobel Prize [4]. 

Is there any risk for data publishers or consumers (e.g., visual applications) to reuse “safely” terms flagged as “unstable”? 
Do you know any study on this type of questions? 

Any experience or thought is more than welcome to propose a more rationale answer to my project partner.

Best,
Ghislain

[1] http://www.w3.org/2003/06/sw-vocab-status/ns# <http://www.w3.org/2003/06/sw-vocab-status/ns#> 
[2] http://lov.okfn.org/dataset/lov/vocabs/vs <http://lov.okfn.org/dataset/lov/vocabs/vs>
[3] http://linkeddatacatalog.dws.informatik.uni-mannheim.de/state/ <http://linkeddatacatalog.dws.informatik.uni-mannheim.de/state/>  
[4] http://data.nobelprize.org/ <http://data.nobelprize.org/> 
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Ghislain A. Atemezing, Ph.D
Mail: ghislain.atemezing@gmail.com
Web: https://w3id.org/people/gatemezing <http://www.atemezing.org/>
Twitter: @gatemezing
About Me: https://about.me/ghislain.atemezing <https://about.me/ghislain.atemezing>