MAXDOP Settings When Exceeding the Recommendation

I have an Sql Server 2014 Enterprise running on VMWare with 32 logical processors assigned. Based on Microsoft recommendation the MAXDOP should be set to 8. However when I run a large query against multiple large tables:

With MAXDOP at 8: 7 Minutes With MAXDOP at 16: 3 Minutes

My questions is what issue I could encounter if I to set the MAXDOP to 16 which is half the number of logical processors?

Thanks in advance