Agreed.
BUT I'll point out: Depending on your main home computer's specs and your use of it, you may not need to dedicate a computer for this purpose.
When I was first looking into this, I was expecting that I'd need to buy a computer to be my Home Theater PC (HTPC), just dedicated to being my DVR. I wanted a Mac Mini for this, but that added enough to the cost that it kept me from pulling the trigger. (a Mac Mini at $600 or $700 is comparable to the cost of a Tivo with lifetime subscription, arguably)
But then I decided to just try using the EyeTV setup with my existing desktop computer, a MacBook Pro 17" mid-2009, Intel Core 2 Duo 2.8 GHz. This is our main home computer, which my wife and I use primarily for web browsing, e-mail, iPhoto, and iMovie. We basically use it as a desktop computer, with no need to move it from the desk since we got our iphones and an ipad.
I expected that the performance impact of running EyeTV in the background, especially with the transcoding exports, would be too much of an annoyance during our regular use of the machine and would convince me I that I did indeed need a separate HTPC. But I figured I'd try, so I bought an EyeTV One tuner and the software used on Ebay. I figured if it didn't work out I'd just resell the tuner/software on ebay.
To my pleasant surprise, I found that the transcoding, while creating a noticeable increase in CPU cycles and usually triggering the computer's cooling fan, didn't actually impede our use of the computer significantly. We could still use iPhoto and iMovie happily while a transcode (EyeTV --> iTunes) was taking place. Sure it would cause a momentary (several second) hang once in a long while, but it always resolved fairly quickly. Enough that my wife didn't think it was worth complaining about.
This meant I wouldn't have to buy a HTPC at all: I could just use the computer I already had.
I have been running the system in this way for the last year and a half: The 3.5 year old machine is always on (sleeping when it can), EyeTV is always on recording and transcoding shows, and iTunes is always running to serve my Apple TVs. We just sit down and start using the computer for regular home tasks whenever we like, whether a transcode is going on or not, and it has not been a problem.
Your results will depend on your own machine's specs. But I can tell you that dedicating a computer to just be your HTPC is probably not necessary if you have a mac from the past 3 years or so.