>>4405911My first thought would be that the dual SD cards of the T5 would be huge. Video wise the S20 has some advantages with open gate and less crop, but it's gonna be pretty similar.
The T5 is also weather proof, but I bet the S20 would be fine in light rain anyway for outdoor stuff.
Technically, in the literal sense, the T5 is going to be much better at photos with higher MP and I think it even has pixel shift for some mega res shit, but is that useful to you really? Most people don't get wedding photos printed on large prints or canvas, but ask your friend what his main clientele is. If they are "high-end" and like to see big numbers you might be able to swoon more people by saying you have X mp shots to give them or something.
The S20 might be more comfortable too, and customizable wheel vs ISO/SS could be huge for you.
Does your friend have any thoughts? What is he shooting with? Try to round out his weakness if he has a more video/photo oriented camera.