Advice - school photography setup

I am the school photographer (and a teacher) at a K-8 private school. I have found that carrying two bodies with me gives me more flexibility and adds more keepers to a shoot. But I am not sure what the best gear setup would be given my equipment. I use the following for my indoor school photography:

• Canon 7D
• Canon XS
• EF 85 f/1.8
• Tamron 17-50 f/2.8 (non VC)
• Speedlite 430 EX II with StoFen diffuser

Today I had the 7D paired with the 17-50 and the Speedlite; and then the XS paired with the 85. Got some great shots from both setups, but I am wondering what would make the most sense.

1. Should the speedlite go on the XS, which has terrible ISO performance above 800? I try not to exceed even ISO 400 on it. If so, I probably have to move the 17-50 with it, which at f/2.8 isn't always wide enough without a flash.
2. Which lens would you put where? My original thought was that the 17-50 provides more versatility and therefore would be used more, and therefore should go on the better body. But the 85 is so sweet and, IMO, can produce better images in the right circumstances.

Any other equipment you'd recommend? BTW, I shoot video with the 85 on the 7D with a Rode VideoMic and tripod, and the results are stunning so long as the subjects are relatively static.


Thanks in advance.


Brian

My advice is to put the 85mm f1.8 on the 7D--the faster aperture combined with the better high-ISO performance will allow you to capture more "keepers"compared to using the 85mm on the XS. Using the XS with the [slower] 17-50mm f/2.8 coupled with flash allows you to use lower ISOs using flash while still getting decent shots.


That makes the most sense to me, at least.

Agreed to what Sean says.

My philosophy is this: don't shore up your weaknesses: reinforce your strengths.


In this case, that would be to reinforce the 7D's low light strength with the f/1.8, and allow the XS's low light weak spot to be even weaker by giving it the f/2.8.


Of course, you really need to judge what will provide you with the best shots.If you think you'll use the zoom more, then I would put it on the 7D to make sure it's utilized the best.