As far as being a time sink, after getting back into the series all the games have taken me probably somewhere between five and fourteen months to finish, so the sixty hours or whatever that they take gets pretty spread out. Although I'll admit that rather than playing for a few hours a week and I'll binge and then not touch it for two months.
Did you ever play any of the other Spiderweb games? I got the in a steam bundle. I tried Avadon and it was okay but not really worth the time it takes to finish. Some good ideas but the play is ultimately kind of bland. That leaves Geneforge and Nethergate, which should all take me a few years to get through. Jeff Vogel says he's remaking Geneforge and that he's going to start a new series with Exile type graphics. That will probably take up the rest of his career.
btw I thought it was funny that alot fans who got into Avernum via Steam were confused about whether it had some Star Wars type story structure because 4 is the earliest game they put on Steam.