Will it be enough if your sinking? No. Will it be enough for regular bilge pump out, yes.
IMO you should have a main bilge pump and second emergency back -up bilge pump in the case that the main doesn't work or you have an emergency.
If your only running one, I would probably replace it with a 2500gph pump.
Read this! http://www.yachtsurvey.com/bilge_pumps.htm
Ive tested my dual 800GPH pumps and was surprised how long it took to pump out 15-20 gallons of water, couldn't imagine going out in the ocean with a single 750....
On my 23' bowrider I'm running two rule 1500 GPH pumps, each with it's own thru hull and hose. Only one has auto function with manual override.
you only need a bilge pump if you own a metal boat with reevits !
disclaimer.......this is an iboats joke.....do not follow this advice