The dvr portion of my RCN DCT6412 works fine, although I don't use it for series or recording 2 shows at once. (Only subscribing to Cinemax and Starz for the HD now, since I've co-subscribed to NYC TWC, too, after they added ESPN2, HDNet, etc.)
Mostly use the 6412 DVR for watching/recording the network shows. That's because, compared to my TWC SA8300HD, the 6412 likely delivers ~1335 lines of resolution from HDNet's Tuesday 6 am ET test patterns while my 8300HD provides 1290 lines maximum. Not positive about the 1335 since that was measured earlier, while I got HDNet, with the single-tuner DCT converter model. 1335 vs 1290 is a very close call PQ-wise, but the 6412 does seem to have slightly better motion-video images.
Curious what other max resolutions others may be getting. I use this technique
for HDNet measurements. DIfferences between RCN and TWC might be a combination of different filtering (TWC has said it uses resolution-trimming rate shaping), the system bandwidth loading differences (more TWC channels, VOD use, etc.), plus the two converter output circuits.
Also, wonder if anyone using a CableCard with RCN can match the reading from FredB, with TWC in Calif., ( 1600 lines
), which may exceed the effective resolution
(resolvable detail) of any programming after MPEG decoding. -- JohnEdit: This updated post indicates FredB's 1600 CableCArd measurement wouldn't have been possible with a 1366-line display panel.