Light source change during growth

I was thinking of conserving on my electric rates by starting my autos on my T5HO lights 20/4 for the first 3 or 4 weeks then over to my Sun System 315W LEC for the rest at 18/6.

Will they not like that change in light type?
Any harm in doing this yield or potency wise?

They will be fine ... You are following a HIGHER daylight schedule to a slightly LESS daylight cycle . You should be nearing Preflower stage anyways ... Just keep schedule until harvest.

I always start my seedlings almost the same way cept I use CFL first 2-3weeks under that then under the LEDs they go never had an issue so far