Yes, it is most certainly worth it.
Granted, it will not bring you mimmediate ROI, aka instant signups - but what it does provide is the ultimate in advertising: brand recognition.
Brand recognition is "up there" on a par with word-of-mouth advertising, and I guess you could say that at certain times, they are hand-in-hand.
PingZine!'s prices are very, very affordable - having spoken with them on a number of occasions, and being in the process of sending our first print-ads out with them.
TheWhir, whilst a little 'off-side' with their magazine, have relatively good pricing too, especially considering their name, and how established it is, in the hosting sector.
PingZine does win over for me though. It has a following, and a good distribution base. The distribution problems of the past are also behind them, for the larger part.
Art, I have an idea that I would most certainly think you would find beneficial for the HD community - providing you with exposure, aswell as your advertisers also.
Drop me an email if you are interested, Artashes, and I'll zip you it over.
Simon