I've been diving a VT3 as my primary computer for four years, 414 dives, absolutely no problems and easy battery change. I dive a Geo2/SPG backup, have not needed them to date. I've been diving Oceanic computers since 1999, I do not have the problems with the interface that others report.
It is my impression that the only major difference between the 4.0 and the 4.1 is deletion of the buddy pressure check function, there my be other changes I'm unaware of. The VT4.1 lists for $1100, Oceanic currently has a trade-in deal for a 20% discount, $880. $600 seems to be a pretty good price for a VT4, it should come with both the download cable and OceanLog software.
There are quite a few hoseless AI computers out there, I'm not sure you can get a better price than the one you shared, you sure can pay a lot more.
Good diving, Craig