In the age of 140-character tweets, the question of long vs. short copy may be moot. But I still get asked this question, usually in the practical context of budget.
You see, I charge by the word. (Yes, Marco, including "a" and "the").
Reader reward
My clients understandably want to know how short we can make an article and still get our point across. The answer is, It depends (not on your budget, as in: How many words can you afford?) But on who your readers are, where they're going to see your piece, why they will want to read it, what you want them to do when they're done, and what's in it for them.
The media diet of the average business reader includes a wild mix of on- and off-line sources--from syndicated news feeds on their smart phones to print periodicals in their office "in" baskets. Our article has to rise to the top of the "to read" list. When it does, will the reader have 3 minutes or 20 minutes to take in the information and get something out of it?
Long explanations
Experts have found that people who are motivated to solve a complex problem will read long articles in search of credible advice. In fact, they expect to see demonstrated expertise and a proven track record before making buying decisons on big-budget items.
This is when white papers work. A 3,700-word white paper proved to be invaluable to one client, whose complex product was expanding into a market of well-entrenched competitors. Likewise, a nearly 4,000-word white paper positioned another client as a thought leader in a new territory.
Short take-aways
People who are scanning the headlines, skimming sub-heads and bullet lists and skipping dense copy will be better served by short news snips, quick how-to tips and succinct success stories.
I recently asked a client to pick one or two of her favorite articles that I've written for her newsletter. She chose a nearly 1,200-word case study with in-depth details and a 270-word case study with strong metrics. Both stories are powerful selling tools for her company.
Another client has dedicated an entire digital magazine to 700- to 1,200-word user stories that illustrate their product benefits. These stories are routinely picked up by industry trade magazines.
Content sells
Bottom line (of this 400-word post), long and short formats each have their place. IMHO, long copy sells expertise. Short copy sells.