Very good question and this has been covered in this great moz article: http://moz.com/blog/after-penalty-removed-will-traffic-increase
Will it help, maybe not in the short term - but if you do nothing you are running the risks of being penalised further down the line and losing all your rankings. Thats the worse case, the best case is by removing the old links your rankings increase. I would never really leave bad links, as you will always be looking over your shoulder waiting for Google to strike.
Remove them and then concentrate on getting some quality links to your site to help boost rankings.
With Google you can never really predict anything any more and you won't really know the outcome till you have removed the bad links.
Worse case: you remove the bad links and your rankings don't improve - but your no longer looking over your shoulder waiting to see if you have been hit by the next update.
Best case: You suddenly jump up in the rankings and you no longer care about the next update, you actually look forward to them, to see which off your competition has been hit.
You will probably get neither of these by removing them, you will probably see a little improvement but nothing massive and you won't have to look over your shoulder.
I know I haven't really answered your question - but even if Google was to answer this question, they would only be guessing as they can't 100% accurately say what will happen as its all machine learnt.
Andy