Preamble: I'm working as reverse engineer in the field of malware in an research institute
In my opinion, even though they may be some overlap, these are completely different disciplines and both leave room for further specialization.
For example, most reverses focus on either programs or firmware, while the mobile and bytecode are more exotic disciplines which are often combined with the main discipline.
Of course a good reverser will be capable of reversing both firmware and applications, but will have problems if the focus is shifted in either direction e.g. when a firmware reverser has to reverse highly obfuscated malware.
You can always try to be a jack of all trades, but you won't be able to specialize in each direction. Although both reversing and pentesting may seem manageable at first, you'll notice that they run deep on some topics.
edit: Nontheless, I'm voting to close this topic because its mainly opinion based. No one can make this decision for you. You could try reddit for other opinions.