It can be a real big issue.
There are really two problems, only one of which can be overcome.
The first is the pricing. Yes, it's true that if you buy at a discount, you will also be expected to sell at a discount. That's the point Leonard is making. So you make sure you get that needed discount upfront, because that's what it'll take for you to have a chance to sell.
The second problem is more serious. You're going to be substantially narrowing the number of people who'll even consider buying. Same thing happens with houses close to highways or high power lines. Some people won't do it because of safety concerns--theirs or their children's. Or their pets'. Some are concerned that they won't be able to adjust to the noise and shaking of trains going through their back yards. And no matter how much you reduce the price, some people simply won't buy. That means if 20 people take a look at a similar house 3 blocks away, maybe only 10 will take a look at yours.
If you understand that and are getting a sufficient discount to cover the first point above (and you say you are), then you might consider moving ahead. But please understand the difficulty you'll run into when you want to sell.
Hope that helps.