I have use A200 with Minolta 5600 before. Using above photos as sample, I won't even bother to shoot at ISO800 if using flash unless I am doing telephoto (subject 5M or further away) or flash is off. Technically, if your subjects are just 3m away from you, ISO400 with bounce flash on is more than sufficient. There is no reason to bump up the ISO to 800 or higher unless you want to see all the noisy crowd behind.
If you have set your flash on auto, regardless of the ISO your subject will be more or less similarly well lit. The only difference is that your background will be darker for low iso and brighter for high iso. And of course at high iso, noise will come in.