If you have to do it its a good way to save heaps of time, but that is usually taken up cleaning out the fridge after the krausen explodes out of the top of the fermenter and coats the fridge and floor lol
I have never noticed off flavours, a very slight difference sometimes better sometimes not. I brew 42lts and the beer that goes ontop is the same as the one that came out. Also when I get to do a side by side the first one has been in the keg for 7-10 days longer so that would affect it to.
Gelatin is fine in the trub. So is hops. If concerned, rack the beer onto gelatin in another vessel.
If your method is clean, sterile and on par with beer style, go for it. No issues like tyreman suggests if done correctly and with knowledge behind you.