A previous version of this question focused too much on my personal situation. The current one aims at being more generic.
The main question boils down to what are the advantages and disadvantages of having a broader PhD thesis?
In the context of a PhD student possibly working in a interdisciplinary field, what are the consequences of working on two (or more) projects, both related to the overall field but each project not directly related to each other? This is assuming there are no major concerns about graduating, the thesis committee accepting or being able to produce quality research.
More in particular, what are the (academic) career consequences of that? I would imagine it can make it easier to find a postdoc position, since the range topics you've worked with is larger, but how is it perceived?
I assume one of the major downsides is possibly the lack of focus. If it is still possible to achieve good research results in both areas (but clearly having fewer papers published in each subfield), are there other problems? Is it usually frowned upon?