Mentioned earlier I started subscribing to RCN in Manhattan along with TWC just to get RCN's 4-channel HD tier (2 HDNets, ESPN-HD, and Discovery Theater, the latter also now on TWC). I now use my RCN DCT6208 HD converter DVR (digital video recorder) for most HD viewing because it doesn't have the faint contrast-spoiling fog of my TWC SA3100HD converter. My earlier RCN DCT5100 also provided a better (fog-free) picture. If RCN can supply stable, clear images in Manhattan, via fiber links and good cable linkups to sets, IMO similar-quality images should be possible elsewhere.
I've found, with 3+ decades of dealing with TWC/RCN here, that it requires persistence to get the quality that's possible with cable. There's endless minutia that can screw up. A month of so back I added all the premium channels to my RCN basic/HD subscription. But while basic (noisy analog) and HD came through, none of the premiums did. A technician found a bad cable link from the building hallway; analog cleared up and the premiums worked.
Duplicating the premiums, which I also get on TWC, is required for a while to make full use of the 6208's single-tuner DVR so I can record anything playing on the RCN 6208 while watching anything else being cablecast via TWC. If RCN introduces the dual-tuner 6408 DVR/converter this summer, it lets you watch one channel while recording another. RCN can tell you whether they're distributing 6208s in your area. -- John