[thicknavyrain]

I do wonder about this a little, but so far I haven't seen anything implemented elsewhere in my field that hasn't been possible to do with our existing code. In fact, I have spent a fair bit of my time replicating others' results with our code and getting sub-percent level agreement.

However, I guess one drawback is that a lot of the things we currently implement are all written from scratch (for very standard things such as numerical differentiation and parameter optimisation), which has the advantage of having "control" and more understanfing over the code, but less time saving/potentially not as efficient as using pre-existing libraries.

[quadruplebond]

I agree, it is very project/field dependent. There are times when a painful redesign might pay off in the future, but I am sure there are also times when it is a waste of effort. In your case a redesign might have been a waste, you are in the best position to judge this.

[ryanpepper]

I use Python for most things and write C extensions which can use OpenMP or CUDA and which are hooked in via Cython for the slow parts. Find this works well, although it can lead to you duplicating things unnecessarily sometimes (needing a C function to be callable by Python requires you to write a wrapper for it).