Second DVR choices?

[#1]

I am considering switching to FIOS from cable.  I currently rent two DVRs from Comcast so that I can record more than two shows at once. They are different brands and each has their own remote.  I have been told by Verizon that I cannot get a similar set up with FIOS using their DVRs -- i.e. only one brand will work.

Does anyone know of an alternative?  

Is there a DVR that I could buy and hook up using a FIOS Cablecard. 

If I bought something like the TIVO four tuner DVR that is listed on Amazon, could I use it with FIOS *without* getting a TIVO subscription? 

[#2]

Tivo DVRs won't work unless you pay the subscription.

You could build a Home Theater PC and use the Ceton Infinitv 4 card with a cablecard - it has 4 tuners and will record all 4 at one time.