The default ones shouldn't be a problem (unless if hibernate sensor pack is placed and active).
I would rather investigate further which methods are beeing reported (method dashlets/hotspots) and are really fast or the count number is really high...This way (taking care not remove a core one!) you can clean your purepaths and improve the performance of your installation!
Hope this helps!
I always proceed on a lab/des/pre enviroment prior to those changes, even with small ones! Bad experiences in the past make me be more cautious...
If not possible, isolate one agent on one system profile and check the results!