It would not be safe to simply decided to raise the gear in response to an engine failure, as you would have already lost performance, and gear retraction is often a high drag sequence.
Couldn't agree more...
In VMC, terrain in sight, you can go on according to what you see. Probably doing well most of the times.
Even if there are no guarantee for anything to work at 100%, it would just be strange to go on ''probability''...Especially when aircraft performance, in other cases, are so detailed and safety oriented.
On the other hand...
As stated above by Wizofoz, there seem to be some sort of tables for that very special config. Now i want to know how common those tables are? Just curious.