Hi, I'm sorry I'm just getting back to you now. FYI to everyone, this is Crazy Season and everyone should expect a long wait for replies (through the end of the year).
First, just a note: we have a total of 6 CATs. If you did the first one free, then you have 5 more after that - so maybe that's what you meant by 4 out of 5?
Re: the GMAT Exam Packs, as you noted, the good news is that these are real test questions - so the test is the closest to the real thing.
The bad news isn't that they don't provide explanations (they're explanations aren't typically fantastic anyway - they're not in the business of helping you get better!). The potentially good or bad news is that, as far as I've been able to tell (so far), many of the questions used in Exam Pack were originally released many years ago and are floating around out on the internet.
The good news is that lots of people have discussed them, so you can find solutions by searching. The bad news is that you might already have done these questions yourself if you spend lots of time on forums / searching for free problems floating around.
(I really don't recommend doing that, but I know lots of people do!)
800Score does offer more detailed feedback. I haven't taken them myself (I can't, because I work on our own CATs - so I have to avoid competitor products!), so I can't tell you how good they are. I've talked to at least one instructor who liked their quant but didn't care as much for their verbal, and one instructor who felt the opposite. :) So they're probably good but not great.
Re: feedback, data, you can track one important thing yourself for Exam Pack CATs: timing. Use the "lap" feature of a timer (most smart phones have this built in) and just hit the button every time you finish a problem. Finish, put your answer in, hit the lap button, start the next problem.
When you're done, you'll at least have your per-question timing which is huge!!
You won't be able to see at a glance that you were struggling with, say, triangles, or SC modifiers. You'll have to look at the individual questions to figure it out (and google the problems to find solutions - the solutions will tell you what was being tested). So it will take some more work, but that is one option.
My next question for you: You've taken 5 exams so far. Did you spread those exams out over a long period of time? I just want to make sure that you're not taking exams too frequently. Read this:
https://www.manhattangmat.com/blog/inde ... many-cats/