Omitting one space makes dictionary attacks completely impossible.
Just thought I'd point out that omitting any number of spaces from only six words only makes it 32 times more difficult to brute force (for each of the five spaces between the words, the space would either be present or not present, thus yielding 2^5 combinations of spaces). Given the math of how difficult it is to crack six words that are all within the top 2,000 most used words (it's very difficult, see math below), multiplying by 32 doesn't change the result much. It's probably unnecessary.
Math:
Assuming "3hjD;kR7" takes 6 hours to crack, that means a computer can crack (26+26+10+10)^8 combinations in 6 hours. That means it can check 2,888,816,545,234,944 passwords per day.
Using 6 of the most common 2,000 words is 2000^6 = 64,000,000,000,000,000,000 combinations.
64,000,000,000,000,000,000 / 2,888,816,545,234,944 = 22,154.
So it would take 22,154 days (or about 61 years) to crack your password, even if you used exactly one space between each letter. Making it take 32 times longer doesn't really matter too much at that point, especially if you change your password every year or two. Plus, the people trying to crack your password are going to try for, at most, an hour brute forcing your password. Then they'll move on to the next guy's password (assuming they got all their data in a batch, which they probably would).
Only if someone with a good computer or cluster of computers is targeting you specifically (i.e. you're a celebrity or political figure) would additional security be worth it. In that case, I would add two more words, thus making it 4 million times harder to crack, as opposed to removing random spaces (which would probably be harder to remember).
Here's a link to the top 2,000 words in English (I found this during my research, and thought it was interesting):
Top 2000 English Vocabulary Words used in Speaking