As you usuly land with less flap when on one engine which gives a greater approach speed, maybe thats it?
Routinely landing with reduced flap in the OEI case is not explicitly an Airbus procedure unless overweight (although CONF3 is of course a valid option). In any case, as CONF3 is an approved configuration, no landing distance procedure (beyond the notmal requirement to check your landing distance) is required.
Some ground spoilers may not be extending...
Care to elaborate on why you think that may be the case? I assume you're not an Airbus pilot?
Vilas' answer is spot on.