Japanese modeler Asayume received samples of the upcoming HGUC Unicorn Gundam in both modes, and has built the Unicorn Mode. ^^
Not much increase in articulation range as compared to the MG version observable at the moment from the poses above, but I'm sure they are more stable as the transformation gimmick is omitted.
The last image seems to show that the HGUC version has shorter thighs as compared to the MG version ^^;
Official release date: 19th (more than a week from now ^^;) Unicorn Mode - 1,575 Yen (inclusive of tax), Destroy Mode - 1,890 Yen (inclusive of tax)
All images are from Gunpla Blog of Asayume: Link 1, Link 2.