I find that owners I work with for the most part find adding their signatures cumbersome and a waste of their time (and they're always losing their sign-on information)...
Regarding LPE's, for the most part the exemption is quite small, so why have an LPE sign-off at all, when it would appear that at most you remove a table or two from documentation requirements, rather than the entire template which seemed to be how the LPE sign-off process was portrayed initially with LEED v3.

Linking data is fantastic! Love not having to worry about what team member is putting into individual credits! Do not love that dates (such as completion date) don't auto-fill throughout.