Reproducibility -- I dunno. A re-implementation seems better for reproducibility. The paper is the specific set of claim, not the code. If there are built-in assumptions in your code (or even subtle bugs that somehow make it 'work' better), then someone who "reproduces" by just running your code will also have these assumptions.
Coding time -- are you sure? Professional coders are pretty good. If you have, for example, taken the true academic path and written your code in FORTRAN, there's every chance that a professional could bang out a proof of concept in Python or C++ in like a week (really depends on the type of code -- EIGEN and NUMPY save you from a whole layer of tedium that BLAS and LAPACK 'helpfully' provide). Really good pseudocode might be more useful than your actual code
Another note -- personally I treat my code as essentially the IP of my advisor. (He eventually open sources most things anyway). But do check on the IP situation if you want to open source it yourself. If you are working as a research assistant, some or all of your code may belong to you University. They probably don't care, but it is better to have the conversation before angering them.