I wanted to ask regarding khilt baynariwaayat [mixing different ways of reading the Qur'an].

Question
I wanted to ask regarding khilt baynariwaayat [mixing different ways of reading the Qur'an]. What is the stance of the scholars with regards to not sticking to one riwaayah when reading but mixing the ikhtilaaf taking into consideration that the 7 ahruf according to a vast amount of scholars is 7 possible differences. Obviously when reciting in this way the qirah will not be attributed to one specific imam, as this would be incorrect.

jazakallah kahir.

Answer
The best answer we can give is that of Ash-Sheikh Abdulaziz 'Uyoon As-Sood in his poem on talkheesi Sareehi-n-naS fi-l- kilimaati- l-mukhtalafi 3an Hafs;

If mixing [them] is detested or faulty     and its forbiddance is more than its correctness.

The scholar Adh-Dhabba3 said that mixing turuq together and assembling them together is not allowed.
 An-Nawawi said in his explanation of Ad-Durrah, that mixing turuq and is haraam, or detested, or faulty. 
Ibn Al-Jazaree divided this issue up into degrees.  If one of two ways of reading is organized with different words in a way to convey a meaning and the other way is organized a different way and they are mixed together, it is haram.  If one way of reading is mixed with another so that Arabic grammar rules are violated, then it is not allowed.  If however the two mixed ways do not violate the organization of the special words or Arabic grammar but supposedly being read as a riwaayah, it is not allowed; if it is not read as a riwaayah or transmission just in ones tilaawah [usually out of ignorance], then Imam Ibn Al Jazaree allowed it, but it is faulty or looked down upon by the imams of recitation.

The Qur'an was revealed in 7 ahruf, but it is mistaken to think these 7 ahruf are limited to the seven qira'aat outlined by Imam Ash-Shaatibiyy or the ten qira'aat which includes the way of Ash-Shatibiyyah and Ad-Durrah, or the ten grand qir'aat outlined by Imam Al-Jazaree in an-Nashr.  Each of the qira'aat have variances or allowed differences within themselves, so possible differences in an aayah are often more than seven or ten.

Each of the ten qira'aat we have today have authentic chains of transmission going back to the Messenger of Allah, peace and blessings of Allah upon him, and each stand on their own.  We should not purposely read in a way not revealed by Allah or without a sound transmission to the Messenger of Allah, and mixing different riiwaayaat or turuq would be just that, if done on purpose. 
And Allah knows best.