Referring to LASORS, it looks like you would get a cross credit on the comms papers, Air Law and HPL.
I'm not 100% familiar with the CPL/IR exams route, but from what I can see on CPL/IR exams there is one navigation paper, where ATPL this splits into Gen Nav and Radio Nav.
I would recommend you do the full ATPL exams. You will probably find the training package slightly cheaper, since all the exams are in one package, and you will find the online question banks more comprehensive since this is what most schools are geared up for.
You may find you end up learning a lot more stuff about operational procedures, and jet engines which you may never use, but on the other hand if in 5-10 years time you suddenly change your mind, you would already have the ATPL exams under your belt. Otherwise there would be more groundschool in the future.