I might be the best person to provide you with answers as I am pretty new to the site...but I have spent about ten hours in the last few days researching this topic, albeit for a two year old. She is reading very well, and although she learned with YBCR, she seems to love LR. I have learned through some great advice from fellow members, that have much more experience with LR, that I can customize LR to meet her needs...(thanks everyone for the terrific advice and coupon recommendations!)
So the upshot is, for math, it seems a bit different...I did the trial for LM, and bought the Doman math set because it is easier for me personally to have them readily available whenever she seems receptive...she has been able to look at quantities and use various tools to count up to thirty, and we have been using a hundreds board at night for what I call 'toothbrush math.'. As we brush her teeth, we quickly count to one hundred whilst my beleagured husband points at the chart with one hand and moves beads on the abacus with the other! I think I pretty much ruined her for simple subsidizing because I wasn't aware....so while we are still attempting LM, (she says she already knows 'Maff', so she is teaching her most prized stuffed animal, who unfortunately cannot read or do math! A, giggles because whilst she knows that this is pretend, is motivated to learn and read aloud to her poor, ignorant friend

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So depending on where your child is at with numbers, I think the best advice, after hours of research, is that if they have counting abilities, number sense, and a general appreciation of simple number concepts, save your money and try either JonesGenius or RightStart. Do the LM trial and see how much your child seems to like it, but it seems like the further they are in their understanding of how numbers are useful in the world, the better use of resources seems to be moving up a level, at least chronologically...also, my child already seems much more interested in math that she can see a use for. She learned equations for numbers 0-5 by sheer accident on my part. She is one of those kids that responds well to transitions if I give her a five minute warning: (we have to leave the park in five minutes... Okay, mommy said five minutes, and one minute has gone by, so now we have only four more minutes of playtime...so on and so forth...then one day I said "okay, your five minutes are up." she sadly looked up and said "zeewo minutes wee main, time to go home!, but came willingly!" I had no idea that she had somehow absorbed the concept of subtraction and zero!
I was truly worried that I would be missing an opportunity to give her a solid foundation in mental math, but this doesn't seem to be the case.
Good luck, and hopefully someone on this forum will have an older toddler they tried LM with...