“Not only . . . but also” can be useful to show contrast. But it can also be redundant, as you say. To my copyeditor’s eye you still have superfluous words in your preferred form:
CookingWithGas is experienced in cooking and in playing the guitar.
OR
CookingWithGas is experienced in playing the guitar and cooking.
With the “not only… but also” construct you create an expectation of some relation between the skills mentioned in the two parts of the sentence: for example, “CWG is experienced not only in short order cooking, but also haute cuisine” or "CWG is experienced not only in classical piano, but also in playing jazz guitar. " If the skills aren’t related, then just use ‘and’ - “CWG is experienced in cooking and in playing guitar.”
Colorful and interesting writing/speaking sometimes uses expression that deviate from what would have been your own first choice. Luckily, there are usually several different ways in which a sentence can be worded.
OK, so here’s the concrete example that triggered the question. My company is writing a proposal and one author included the following sentence. Feel free to critique.
Our company has demonstrated the ability to not only develop a complete technical solution but to partner with our customer’s business team and application support contractors.
I don’t like to use “not” and “but” because regardless of the intended meaning of the entire sentence, they create a subliminal feeling of “I’m saying something negative here.”
I suggested
Our company has demonstrated the ability to develop a complete technical solution a[RIGHT][/RIGHT]nd also to partner with our customer’s business team and application support contractors.
In some cases, especially in shorter sentences, I see where this could be effective (the one-up example offered by OffByOne, or the contrast suggested by Andy L).
But I don’t like it they way I’ve quoted it above.
Yes, but further, you are recognizing the larger context of the discourse. It could be–within this particular business of CookingWithGas’s workplace–that companies usually offer complete technical solutions, but seldom also partner with the customer’s business team, etc. To emphasize how this company distinguishes itself, the writer has chosen this particular construction.
We need to remember that sentences don’t occur isolated. They occur in paragraphs, which are part of larger discussions, which are part of larger social, political and commercial contexts.
In this case, I’d suggest making an even stronger connection between the two parts of the sentence (see below - bolding provided just to emphasize where I’ve changed things) - as long as you think it’s fair to say that part of the process of developing a complete technical solution includes partnering with the team and contractors
Our company has demonstrated the ability to develop a complete technical solution by partnering with our customer’s business team **including the **application support contractors.
I’d say that the construct implicitly contradicts some expectation of mutual exclusion between related concepts. I’d say your first example fits that better–in that the expectation is probably stronger–but it works in both cases.
This is in line with CookingWithGas’s intuitive preference for using “but” when it is joining a counter to a statement.
This is definitely better. My only concern with it would not be grammatical, but political; by specifying some groups they partner with, they may seem to be excluding others, like the customer’s engineering team. Listing groups can be touchy in this kind of copy. You don’t want to leave anyone out.
“implicitly contradicting some expectation of mutual exclusion” is a nice way of describing how to use that construction. “Feynman not only was an top-flight physicist but was also an accomplished bongo-player” works as a sentence because of the implicit assumption that physicists aren’t usually bongo players (violin players, maybe, but not bongo players); “Miss Johnson is not only an excellent kindergarten teacher, but also a fine 1st grade teacher” is a bit funny as a sentence because we don’t expect those categories to be exclusive (reminds me of the bit in “Deep Space Homer”: “There’s a mathematician, a different kind of mathematician, and a statistician”).
For me, the construct implies that those are the only two things you’re good at.
“CWG is good at cooking.” End of story.
“CWG is not only good at cooking, but also at playing the guitar,” and that’s it.
If it gets any farther, you get into a Monty Python sketch: “Okay, aside from the cooking, and the playing the guitar, and composing sonnets, and riding a bicycle, what is CWG any good at?”
To me this suggests that other companies may be able to provide the technical stuff, but fall short when it comes to the partnering aspects, thus it’s noteworthy that this company can do both. If this is the case, then the “not only…but also” construction is appropriate. If it turns out that the competitors can do both just as well, then it’s marketing fluff and/or a sleazy insinuation against the competitors.
ETA: The example sentence left out the “also,” which makes it a little ambiguous – the “but” without the “also” is what you’d expect if the first part said “not” rather than “not only.”