I read the following in a Discovery News article, and it gave me pause:

Fussy readers will frown at the faulty parallelism of “as much, or more, than…”. After all, we don’t say as much than. Strictly speaking, it would seem a second as is missing: as much as, or more than, the face.
This construction is sometimes called “dual comparison”, and it takes various forms: as good (as) or better than; as well (as) or better than; as bad (as) or worse than – you can add your own adjectives or adverbs to the formula. All are susceptible to the kind of casual ellipsis pictured above.
You may be wondering how acceptable the unparallel forms are: whether they’re OK in semi-formal contexts such as science news websites, for example. Let’s see what usage commentators have to say.
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Bryan Garner says parallelism “helps satisfy every reader’s innate craving for order and rhythm”. He believes the second as “must appear”, and that dropping it is a “common error”. His appeal is to logic. This is also essentially the argument made by Robert Burchfield, who in his revised edition of Fowler says difficulties arise
because both bad and good (as well as other adjectives) obviously require as, not than, in comparisons. The juxtaposition of as and than without intervening punctuation is not logically defensible. Thus the sentence we’re sure they can judge a novel just as well if not better than us (London Review of Books, 1987) needs correcting to just as well as, if not better than, us.
Burchfield says a wiser course is to sidestep the problem by placing the comparative later in the sentence. So the LRB line could be recast thus: just as well as us, if not better.
But this is not the whole story; other authorities are less stringent. Kenneth G. Wilson’s Columbia Guide to Standard American English says the structure
is idiomatic, at least in Conversational levels and in their written representations, but Edited English avoids it because it is often criticized for its faulty parallelism. . . . Particularly in longer sentences, punctuation gets more complicated when you restore the as: He is as handsome and well-mannered as, or even handsomer and better-mannered than, his older brother.
I don’t see how the punctuation gets more complicated there, though: it’s just the usual two commas in a slightly more complex sentence. Here’s an unimpeachable example in Mary Trump’s book Too Much and Never Enough:
Abuse can be quiet and insidious just as often as, or even more often than, it is loud and violent.
The Columbia Guide, in a separate entry, says that only crude faulty parallelisms usually bother us: “we speak and write a good many more that go unnoticed.” Unless we have that “craving” Garner mentions, I suppose, along with a meticulous reading and listening style.
The most thorough treatment I came across is in the exceptional Merriam-Webster Dictionary of English Usage. It says the objections began (as they so often do) in the 18th century, beginning with George Campbell in 1776, and they have continued ever since:
This issue arises from the 18-century grammarians’ concern with developing a perfectly logical language – logical from the point of view of Latin grammar – and eliminating as many untidy English idioms as possible.
It says the locution might nowadays be considered “simply another idiomatic usage” had Campbell not noticed it, and that it is “a venial fault” since readers are not confused by it. After examining the various ways punctuation can affect the construction, MWDEU concludes that it “need not be routinely revised out of general writing that does not strive for elevation”.
A search on COCA suggests that as good or better than – seemingly the most common of these expressions – appears especially in magazines and newspapers, often as quoted speech. But academic occurrences are not unheard of, and for as well or better than are of comparable frequency. A few examples:
He knew the lawn as well or better than she did (Margaret Edwards, Virginia Quarterly Review, 1993)
they scored as well or better than the Swedes on tests of reproductive and contraceptive knowledge (Public Interest, 1993)
third-party settlement can be as bad or worse than negotiation in encouraging extreme claims and positions (Canada–United States Law Journal, 2000)
CPDT training is as good or better than the pre-service training (Education, 2003)
You can click on the following charts for more information on specific instances.
As good or better than:

As well or better than:

If on the other hand you are striving for elevation, and you want to attend to proper parallelism, you can:
1. Add as and use two commas.
2. Place the comparative later. This was Strunk’s preferred solution: My opinion is as good as his, or better / if not better.
3. Rephrase, e.g., at least as X as Y.
Different styles, tastes, contexts and hunches will call for different solutions, and it’s always good to have options.