Are there any Spectrum boxes with 4 or 6 tuners?
Yes. The newer Spectrum worldboxes have 4 tuners. Older Samsung, Motorola, Arris, Cisco, etc. boxes have anywhere from 2 to 6 depending on the model. The older boxes are being phased out though in favor of the Spectrum boxes.
the arris DCX 3600-M is a 6 tuner if you can get that one. though i would go into a store and ask to see if they have any!!! i would avoid the world box with a passion as that's a disaster with the guide being up in the cloud sometime the guide will download and sometimes it won't it will just leave you there with a grey screen with lines going across it doing wonky things!!! and it's only a 4 tuner unit and there's NO clock on it if that makes a difference