Are you staying Standard Definition? Your Series 2 TiVo DVRs can be used with DirecTV, but anything they record will be SD not HD. If you are good with that limitation, then yes they can work just great. You will not need, but I do recommend, that you get a serial to USB control cable so that the DVR can easily change channels on the DTV receiver without needing to use IR blasters. Check out the USB TV Translator at http://patersontech.com/products/UsbTvTranslator.aspx
This works with either SD or HD capable satellite receivers, but will only record in SD even from an HD source. You can record anamorphically so that you get the best 16x9 result in SD possible. If you record in best or high, and view on a good TV set with a decent upscaler, the results are actually pretty decent. Of course if you are using an SDTV, none of that matters, it will look fine.