DD9 was assigned IXL for homework last year, and my understanding is that it is "review-focused" and does no teaching. I am not sure how close to grade level it is - DD asked to, and was allowed to work above grade level.
DD doesn't seem to be a perfectionist, so we haven't had problems there
(but DS might be, so I'm making a mental note of the comments of others - so helpful!).
I think for a bright kid, the early "grades" in math in many of these programs are just too simple.
For example, DS6 uses Dreambox for enrichment at home. He flew through K-2 ridiculously quickly. He complained a great deal when he got to "3rd grade" on Dreambox, because the format changes (it is less "cutesy," probably because many of the kids using it are older), but he is working through it. Dreambox seems to have a teaching component - it is not just testing the kids.
EPGY has lectures - I sometimes cringe a bit when listening to DD use it in the other room, because they DO sometimes sound awfully dry. I have not tried DS6 with EPGY yet, because of the "lecture-style" - seems focused on a slightly older set IMO, because of this. DYS DD9, uses EPGY for enrichment at home, and recently asked if she could try algebra - it is nice that EPGY has all of that (we use OE). Since DD's recent MAP test scores suggest she could be ready, I let her play around with algebra (apparently, it starts kind of slow, too, because DD grew frustrated with it and started telling the EPGY lecture - "I already KNOW this - blah, blah, blah!!!" Um, patience is not her strong suit...). If your DC can handle the lecture-style, EPGY provides a great deal of learning, although I'd definitely try the OE route - MUCH more reasonably-priced and FINE for how we use it.