Yes, C++ is certainly suitable for embedded systems. First let's clear up a couple of misconceptions about the difference between C and C++:
In an embedded micro, you're always going to need to use high level languages carefully if you're concerned about time or space constraints. For example, many MCUs don't handle pointers well, and so are very inefficient when using the stack. This means you have to be careful about passing variables to functions, using arrays and pointers, and recursion. A simple line of C like:
a[i] = b[j] * c[k];
can generate about 4 pages of instructions depending on the nature of those variables.
Whenever you're using any high level language, and you're concerned about time and space constraints, then you need to know how every feature of that language translates into machine instructions on your MCU (at least, every feature that you use). This is true for C, C++, Ada, whatever. Probably all languages will contain features that don't translate efficiently on small MCUs. Always check the disassembly listings to make sure the compiler's not generating reams of instructions for something trivial.
Is C suitable for embedded MCUs? Yes, as long as you keep an eye on the generated code.
Is C++ suitable for embedded MCUs? Yes, as long as you keep an eye on the generated code.
Here's why I think that C++ is better than C even on 8-bit MCUs: C++ provides improved support for:
- Data hiding
- Stronger typing / checking
- Multi-peripheral transparency using classes
- Templates (as always if used carefully)
- Initialisation lists
None of these features are any heavier than typical features of C.
As you move up to 16 or 32 bit MCUs, then it starts to make sense to use heavier features of C (stack, heap, pointers, arrays, printf, etc.) In the same way, on a more powerful MCU is becomes appropriate to use heavier features of C++ (stack, heap, references, STL, new/delete).
So, there's no need to shudder at the thought of C++ on a PIC16. If you know your language and your MCU properly, then you will know how to use them both effectively together.