X-E1 vs nex 7 questions
The Voight 15mm is still likely to have smeared corners with the XE-1. It's your call if Cornerfix works well enough to ameliorate the problem and that you have the time to correct it with software The XE-1 doesn't have microlenses to help with these RF wide lenses, but the native Fuji X wide lenses present no such issues.
If the Sony's color signature is not an issue for you, why not wait until April 8th at the NABShow to see if Sony will bow the NEX 7n ? The NEX 7n is likely to be out in May and prob. will have microlenses like the NEX 5n did, that prevented corner smearing (just a guess).