I once edited Leeds into the Prem with a dream team of players like Ronaldo, Rooney, Messi, Kaka, etc, and thought I was clever by dropping all their reps to 1, had Leeds as their favourite club and loyalty increased to the max, they still wanted to leave at the end of the first season, despite me winning the league. Why? Because I forgot to increase Leeds's rep to Prem club status. Pah!
I did try selling a couple (£50million + 25% sell on for Ronaldo, £65m for Kaka, £40m for Rooney) and using the money to rebuild another dreamteam, but guess what? No one would sign, even for £120,000 per week.
So if you do this, remember to put your rep up too. But not too high, otherwise it's easier to get sacked.
I have tried this and it's really horrible Basically, your players are uber fast, so they just waltz past the opposition, uber strong, so they destroy every attack and a shot on target is pretty much a guaranteed goal. It's fun for about 5 minutes.