PFC pure sine needed on UPS battery backup?

[joewifi]

Using
WS-12-250-AC
WS-8-150-AC
WS-24-400A
WS-6-mini

is it recommended or required to use a pfc/pure sine wave UPS battery backup?

search the message board some posts say NO not needed. But some posts say YES it is needed and problems arise if not using pfc/pure sine. Problems with modulated sine.

So, curious if we can get clarification. Would pfc/pure sine help prevent life of switch shortening issues?

we did have the ws8 on a modulated sine ups and we've had to replace it twice in 9 years. The others switches on pfc or no ups have been rock solid.