+1, I highly recommend making sure the game runs well on entry level rigs, even if it doesn't look very nice (at first - low-quality textures is an art and can be done well).
One of the major reason why Killing Floor 1 was such a massive success was its low requirement: a bunch of friends could play together, even if one or two in the group only had a weak GPU (or an average gaming notebook).
Countless people online confirmed me this, and in my case we could organize LANs games (using spare Steam accounts with KF1, bought during sales for that very purpose) with non-gamer friends (who would have never bought KF1 themselves) thanks to the excellent downward scalability.
For quite a lot of people, Killing Floor was one of the few games that introduced them to online PC multiplayer gaming (since it's cooperative PvE, much more forgiving and friendly than pure PvP) and got them to get a decent GPU. If Killing Floor 2 could do this for newer generations of PC gamer, it would be an excellent news for both the game and gamers
