Air New Zealand Air Points - Differences between ANZ booking engines

I'm in Los Angeles, considering making a booking LAX-LHR-LAX for November. I observe these differences between the older "ITN.net" engine and the newer ANZ booking engine. I would appreciate some comments to my observations.

ITN Engine:

1. Lowest price: Class K, return fare of $637, including $306 taxes.
2. Enables me to select my seats.
3. Prompts me for my old login; upon viewing my profile, I see mistakes in my personal data. After I correct and save my profile, if I logout and login, the corrections do not appear, but, instead, revert to previous data.

Newer ANZ engine:

1. The lowest price is $682, based on $259+$259+$164 tax.
2. No seat selection.
3. No apparent login--just enter new information, which can be saved.

I prefer the price and seat selection of the ITN engine, but I'm concerned about its reliability, since it doesn't seem to retain an accurate database for profiles or updates.

Any comments about the status and reliability of these 2 engines? Thank you.

The Air NZ website actually has multiple booking engines, each with different features and quirks. It has long annoyed me that the features I wish to use are scattered across several booking engines and I always have to choose which feature I want to use (and which I do want to use but not as badly) for each particular booking. You've mentioned a few differences but there are many others, and as each engine gets tweaked from time to time the differences can change. Most annoying. I'd far rather NZ had a single engine with all features available by selecting expert mode, and a simpler cut-down version for infrequent users. Alas, they show no signs of doing so.

I admit I tend to not to log in when using the ITN international multi-city engine, since I've had problems with profiles. Entering just my name and FF# seems to work fine.