Wow - no, I would not even consider this one. Surely just buy a connecting ticket on TK: better product (maybe even a long-haul aircraft with flat beds if you stretch to business class...), and protected on the transfer at IST.
Don't forget that Turkey is now one of the countries from which the UK has imposed the "no laptops/ipads" in hand baggage rule - so be careful what you pack if travelling HBO, and be aware this is creating (at most relevant airports, including I would guess IST) extra waiting at security and/or at the gate.
I wouldn't try this one.