A while back I had an idea to use procedural functions in otherwise OOP code. It's not that bad idea in itself, but I went too far and now backtracking some of those routines back to classes. The other paradigm I've struggled with is the modular thing, which is much harder than I thought. Sometimes you don't want to force classes into a thematic module, because it's easier to keep it separated from others with the possibility to open the namespace in that particular file. Opening namespaces with more than one namespace is sometimes not possible without duplicate names. The distrubution of modules is the hard part in modular design, but it's better than just have tons of classes each in a separate file, because then you have endless include race going on.
I think it's going to be fine, after massive amount of work of course. A weird thing happening at the moment is Teemu's development which is in many ways doubling the amount of work, because I'm using similar kind of re-arrangement of code into more logical compositions and I can't just copy-paste between projects. In some cases I have developed things I can use in other projects, but it's quite rare. However I do benefit from actually figuring out how to do some things, which then can be rewritten for another project. Still, I really could do without having to manage two roguelike projects at the same time.