Obviously, you could be correct. There is definitely a chance that your problem might be software related.
However, there is also a chance that the problem might be something else.
If you want to tinker around with your current tivos before you attempt a product return, then there are a couple of things that you might try.
1 - can you tell us which software version you are on? You can determine this by navigating through the Tivo menu screen and checking your "account and system information."
There is a chance(at least some chance) that your software is not completely up to date. If this is the case then you can try forcing a connection to the Tivo mothership to get your software updated.
2 - are your Tivos connected to a power outlet directly in the wall, or are they connected to UPS devices? Some Tivo users have reported improvement in stability with their Tivos by using a UPS. I have one of these myself. You do not need a big UPS because the power draw from a Tivo is very low.
3 - Which Tivo menus are you using? High def, or standard display? At times in the past, some users have reported that their Tivos behave better in one mode or the other. You can change this in your settings menu.
4 - if you want to deal with Tivo support, then try to get a level 2 support person. In my experience, level one support doesn't do much good.
5 - you might also try to get help from the support forum on the tivo.com website
6 - as a last resort...... you could do an exchange.... over the years, some Tivo owners have reported that they ordered Tivos which malfunctioned, but then they exchanged them and the replacement devices worked fine. I ran into this myself a bit when I bought a new Tivo Premiere a couple of years ago. The first product kept crashing on me but the replacement product that they sent me has been working fine with very little problems.
If I recall correctly, with Tivo, they give you "X" number of days(30, or 45, or something) where you are able to do an exchange at no cost whatsoever. After that, they do charge you something for doing an exchange.
Again, sorry that you are having this problems. It is terrible that you paid all this money and then have to deal with this hassle.
Tivo is awesome once your system becomes stable, and I hope you stick with it. I am a huge fan of Tivo myself, but I will admit that at times it can be a love/hate relationship!