Mendenhall has been bashed quite a bit here (much of it ridiculous) so I am giving some of it back. I don't see Felix as being a major contributor because he will always have nagging injuries, IMO. I hate injuries (as the scourge of all sports) so I would love for Felix to prove me wrong. But I also think that JJ could have foreseen Felix as an injury threat from Day 1 and picked a better long-term back (Mendenhall or CJ). Also, Felix is a one-trick pony to me: wide left, trying to turn the corner. He will need to increase his versatility, otherwise he may never reach his rookie stats again.
Tashard Choice is not in the same league as Mendenhall as a power back. Mendenhall is a #1, while Choice is a backup. I do not agree that you cannot have two strong #1 backs in the same lineup. The Giants were awesome with Jacobs and Ward last year and not so good this year. Miami gets a lot out of both Ronnie Brown and Ricky Williams. I really believe Dallas fans would have loved both Barber and Mendenhall trading carries, along with a change-of-pace back that could have complemented them. Felix was a rookie dynamo but his perceived injury problem became reality both last year and this year.