Moved provisionally to Encryption: EEM Managed for faster support.
Yes we have exactly the same issue with the surface pro 3's. You might find if you plug an external keyboard in you can type the password in quickly but it defeats the object of having a tablet.
We are now looking at McAfee Native Encryption to manage Bitlocker on tablets only and to support some Mac's we are trialing.
Sorry it doesn't really help getting MDE up and running on the surface pro, but the answer back from McAfee is that it is not an issue with the software but with the OEM and there implementation of UEFI Bios standards. We have seen nothing but issues with all tablets we have ranging from the Surface Pro to Lenoovo, HP and Dell.
I wanted to give a final update with a solution. I found this article here: McAfee KnowledgeBase - System becomes unresponsive during preboot authentication on Dell 5x50/7x50 when the Out of Band … . This describes the exact issue I was having, although it specifically mentions Dell products in this article. However, I still followed the workaround using the steps in the product guide, but disabled the out-of-band management instead of enabling it (we currently don't use those features so it did not effect our environment at all). After doing that, I performed an emergency boot to get past the login and enforced the policy. I no longer have any freezing. I have restarted over 20 times now and not once has it locked up on me. I feel pretty confident moving forward now. Thanks!