^^
hmmm..... well, u 1st and foremost need to tell me (if u knw exactly) wether u hv an ACTIVE PFC type of SMPS or a PASSIVE PFC type... smps... coz see, the simple understanding (In general) is this...
1.) IF.... u hv an ACTIVE PFC type of SMPS then go for ----> PURE SINE WAVE based UPS (Wich in APC's case) wud be the SMART UPS range of UPS (not BACK UPS range)
2.) IF... u hv a PASSIVE PFC type of SMPS then go for ----> STEPPED/MODIFIED SINE WAVE based UPS (Wich in APC's case) wud be the BACK UPS range of UPS (not SMART UPS range)
so check ur SMPS manual and then letme know...