It is a wise idea to leave them on.
My mate would often claim that he could see my rear triangle flexing under the strain, especailly when it was wet...
(Sounds like I'm writing for a top shelf magazine)
...With the boosters on, it makes a more positve feel, with very little flex.
I use carbon boosters on my other bikes...no weight to carry! I don't use them on the front with my Pace RC36's because the forks have enough bracing to cope. And carbon boosters aren't cheap as a rule.
1990 Marin Team Titanium, 1991 Marin Team Titanium, 1993 Marin Team Titanium, 1994 Marin Titanium FRS, 1995 Marin Team Titanium, 1995 Marin Eldridge Grade, 1996 Marin Team Titanium, 1998 Marin DH FRS, 1999 Marin Team Titanium, 1999 Marin Mt. Vision Pro, 2000 Marin East Peak, 2002 Marin Mount Vision
1988 Concorde Colombo, 1997 Colnago Master Olympic, 2005 Look KG481-SL, 2009 Look 586
WANTED: Marin Titanium - pre 1990, 1996 FRS, 2007 25th anniversary