[Elecraft] Need help to determine most effective K3 vs KPA500 output

[Fred Atchley]

I have a K3-100 with KAT3 and a KPA500 w/o a tuner. I use an all-band
"Mystery" (similar to a G5RV?) wire antenna. Because of the KAT3, the K3
"sees" a 1:1 antenna match which is good. However, I would like to operate
up to 200 watts out (low power) for the California QSO party.  The KPA500
tolerates a 3:1 SWR at 200 watts across the 20 meter band and in the CW
portion of the 80 meter band on the mystery antenna.

My question is which option is the most effective, 100 watts with 1:1 or 200
watts with 3:1? Keep in mind that both options use the identical antenna and
feedline.

Thanks in advance.

73, Fred, AE6IC