I used similar tools on my 3G with the 3.x series but haven't taken the time or bothered with jailbreaking iOS4. I figured there would be updates relatively soon and wanted to at least give it some time and see how things ran stock. So far I've been really disappointed and I have to agree, 4.0 is not a good upgrade for the 3G. I have to wonder if perhaps Apple should have just made the upgrade unavailable for 3G owners like they've done with the previous generations of the touch.
Overall, 4.0 was not a good upgrade for the 3G.