i have the arris DCX3600-M with the i guide @Satch
The Arris DCX3600-M is a six-tuner box IF you have ODN-Navigator on it. The Humax/Technicolor World Boxes run the new Spectrum Guide and have four tuners, but no clock. I would try to get a DCX-3600 M, the Arris from the store. It will have ODN Navigator on it, which is a newer guide, be MUCH faster, and you will be able to use the six tuners in the box. With IGuide, you can't. You can also ask about another great six-tuner DVR, the Cisco 9865. I have it and love this box!
I Guide is really old. You might also get a box with Spectrum Guide on it if you get the World Box. Spectrum Guide has some bugs but it's getting better. Note that World Box DVR's are four-tuners and no clock, but the same storage space as the six-tuner models. Also, if you have Spectrum Phone Service, Caller ID on TV is not out yet on Spectrum Guide.
In either case, it will be a huge upgrade from I-Guide, Generally, I recommend not swapping boxes, if you have no problems. But here's the thing, you are sitting there with a capable and ready six tuner model DVR, and you can't record with six tuners, because it is running I-Guide. Let us know what you choose to do about this.
The other bugs I've encountered is the DVR or Guide is unavailable messages with a 4 digit code, usually 0000 or another sequence. Hitting "ok" and then selecting DVR or Guide usually solves it. Are these ongoing bugs fro the new guide and world boxes? I hope Spectrum doesn't drag their feet in fixing this stuff. Other than that, it seems to be working pretty well.