Depends on your tolernace and whether or not you are going to go to sleep soon. If you are going to sleep soon there after I would say save your dub for the AM
Most likely you will no recollection of typing this because 10 mg of k-pin will have you f'd for about a day. Unless your tolerant to that much, which is not an enviable situation.
Far from safe. Even at low doses, mixing benzos and opiates is a recipe for disaster and respiratory depression, but 10mg's and only 4 hours since taking it? Horrible idea to use heroin now.
You don't "sleep off" 10mg of Kpins. Sleep isn't a restart button in the game of life sadly. Even if you don't feel the effects you are still on benzos and shooting tar is asking for trouble.
Benzo's are insidious in that the 'high' is most noticeable after they wear off and you go, 'holy shit when did I do THAT'. Imagine the effect of 15 bottles of beer without the presence of mind to realize you're drunk.