I just finished reading over the proposed Guidance Document for Hybrid Appraisals.  My understanding of a hybrid addpraisal is that the information is pulled from a number of sources, some of which the signing appraiser  may not have access to in order to verifiy the information provided.  As a certified residential appraiser, I keep going back to 18VAC130-20-180.  Standards of Professional Practice relating to the Use of signature and electronic transmission of report.  18VAC130-20-180. Standards of Professional Practice.  The information contained in the report comes from different sources, including, but not limited to, other appraisers.  Without being able to question the other appraiser about his/her findings and opinions, it would be a violation of USPAP to sign the appraisal report because the licensee could not honestly sign and send electronically the report because he/she could NOT exercise complete direction and control over the report.  Personally, I would not put my signature and risk my license and livelihood on a report that I could not personally verify.  See Below:

C. Use of signature and electronic transmission of report.
1. The signing of an appraisal report or the transmittal of a report electronically
shall indicate that the licensee has exercised complete direction and control
over the appraisal. Therefore, no licensee shall sign or electronically transmit
an appraisal which has been prepared by an unlicensed person unless such
work was performed under the direction and supervision of the licensee in
accordance with § 54.1-2011 C of the Code of Virginia.