If you use the integrated boxes (DirecTiVo and UTV), the picture quality will be the same as they both just record the DirecTv MPEG stream. If you aren't don't want to run two more antenna feeds and a switch, then you can consider a standalone TiVo and use it to control the HD100.
Minority opinion follows .. I have used both TiVo and ReplayTV/Showstopper. I have researched Ultimate and do not like the construct of its pricing. While I have not used/seen an Ultimate, I can say that the Replay/Showstopper is easier to set up, more cost effective than a TiVo, and the human factors of the menus and program grids are much better than TiVo. The ReplayTV 3060 (a 60 hour unit) is rock solid. If you want to look at a PVR, you should research the forums on all three before you decide.
Since you already have DirecTV I would eliminate any ReplayTV units from consideration. Since there is no combo DirecTV/Replay unit the picture will degraded somewhat over one of the combo units. There are also several other reasons to eliminate Replay:
1.) The Replay unit cannot record Dolby Digital. Both combo boxes can.
2.) The cost. With rebate the Sony or Philips can be found for $250-$300. Even if you add the $249 for the Lifetime TiVo service it is still cheaper than a Replay 3060.
As for which one to select between TiVo and UltimateTV I would suggest reading some of the comparison posts on the TiVo and UltimateTV forums. I have had the DirecTiVo since October and it is incredible. The only advantage that UltimateTv currently has is the 2nd active tuner. TiVo has continued to state that the 2nd tnuer in the DirecTiVo box will be activated this summer. We'll see. Even without the 2nd tuner TiVo has much ore robust software. Some of the TiVo only features include Wishlists, Season Passes, and the ability to distinguish between first run and repeats (I'm not sure if UltimateTV can do this). Good luck.
A forum community dedicated to home theater owners and enthusiasts. Come join the discussion about home audio/video, TVs, projectors, screens, receivers, speakers, projects, DIY’s, product reviews, accessories, classifieds, and more!