I fermented 5.5 gallons of a wheat in a 6.5 gallon carboy and had a fairly violent blowout. I had the same amount of a nut brown in the same container and had no issues.
Additionally, the higher the amount of fermentables in the wort (higher OG) the more vigorous the fermentation will likely be increasing your chances of blowout. The IPA I just bottled overflowed my airlock but didn't blow it out and it was a moderately high OG (1.05).
Why risk it when it only costs $3 or $4 bucks for a tube. Put the other end in a milk jug partially filled with sanitizer solution.
By the way, the picture above is my Extra Light Ale that I just brewed on Saturday. Hopefully it will be like BMC with taste added. I have no way to do lagers yet, so I had to make an ale equivalent.