I did find this so far:
viewtopic.php?f=6&t=9681&p=70654&hilit= ... ore#p70654:
We have found our dc learn their facts through doing Singapore as it is written. However, if you want to add drill of facts, it is incredibly easy to add as there are a whole host of available drilling facts resources available. Adding the excellent mental math and problem solving skills that Singapore is so strong in is much more difficult to add to a different math program that is weak in these areas. Here are Carrie's comments explaining why HOD chose Singapore math, as I think this is incredibly helpful...
...you are more than welcome to choose your own math curriculum to use with any of our programs (and we do realize that there are many excellent math programs to use out there). However, we have tried many of the big-name, and not so big-name, math programs for at least a year each and found many of them didn't fit our family well for a variety of reasons.
Many of the programs were just too time-consuming in the amount of teacher presentation required. As we added more children to our homeschool, I realized a 30 minute math presentation for one kiddo would quickly turn into 2 hours of math presentation when multiplied times my 4 boys. That would leave precious little time for the many other necessary school subjects.
Some of the programs required too much prep. or planning ahead of time prior to teaching. When I wasn't prepared, my students were wasting time waiting on me. Other programs had way too much drill or too many problems daily for my non-math loving oldest son. So, I found I was tweaking which problems to do daily and eventually the programs hardly resembled the original progam anymore.
In keeping with the Charlotte Mason philosophy for math, I wanted a program with short lessons, some hands-on, almost no prep., in a workbook form (to cut down on time spent copying problems) that emphasized higher-level thinking and reasoning along with computation. I also wanted it to be economical if possible. So, when we began with Singapore we knew we'd found the fit for us.
Where the program lacked hands-on in the early years, I added in lessons to include that. The one problem we have found with Singpaore is that the clean page layout and the few problems on each page makes it easy to assign too much daily, thus complicating what should be a short and sweet program. We compensate for that by including schedules in our guides that follow the original Singpore pacing, completing 2 workbooks in one school year.
Our plans are to phase out the hands-on teacher lessons starting with 3A/3B and move toward the textbook/workbook schedule only at that point. With a strong hands-on background from the previous Singapore years, we're finding the kiddos will be ready for that change.
At this time, we will probably endorse Singapore through 6A and 6B. It gets more teacher-intensive after that point, and we most likely will suggest an alternative prior to continuing on to the New Elementary Math that comes after 6A/6B. Since Singapore has such a solid base in problem-solving and reasoning, and an advanced scope and sequence, the switch to almost any other program should be a fairly painless one.
So, to make a long story short, all kids are different, and we know one math program will not fit them all. But, we do want to share what we've found with others in the hope that it may be a fit for some of you as well.
Blessings,
Carrie
Math is a subject that has a finite body of information to be learned, and Singapore does this in a clear, systematic way that encourages mental math. IMO, strong mental math is the goal. It is something needed every day, in every walk of life. These are the top things I appreciate about Singapore...
1. it teaches the "why" behind the "how" of math; it doesn't just drill - it teaches how to "think" mathematically
2. it is strong on mental math
3. it teaches pictorially, which helps dc visualize the mathematic operations they are doing
4. it is strong on problem solving
5. it is short, has no prep, and is consistent
6. it has a strong track record of dc testing well on standardized testing
We really like Singapore, but like any math program, it takes a bit to get into it. I think Singapore deserves a year's try. It will seem different at first, but that's because of all of the above points I listed. If you're going to give Singapore a try for a month, you probably won't really get a good read on how it will go long-term. One last thing, I am a firm believer in the "less is more" theory when it comes to math problems (as well as with things like cursive handwriting, etc.). If a child can show you they fully understand the math concept in 10-15 problems, why would I make him do 50 problems and have him start to rush to get through all those problems and start to have the habit of carelessness? Math should not take forever to do. Singapore looks deceivingly simple - it is not. It is more than difficult enough, but it does not overkill a skill. The HOD activities up through Singapore 2B are awesome, and I believe a necessary part to do with Singapore at the younger ages (that should be more hands-on). However, there is a time to give up the hands-on part of math, IMO, and it has been a good time to give it up at 3A. Our dc are completely different learners and both thriving with Singapore. !
I have not found any need to supplement with Singapore. I didn't learn math this way, but I am enjoying learning it now.

I cannot believe how easy math is the Singapore way - the methods they teach all but take away the need for scratch paper use, or lengthy memorization of steps. I have found it is important not to jump in and try to share my "tips".

They are not helpful, and they confuse the dc. The fact is Singapore often gets to my "tips" eventually anyway - they just teach mental math methods first.
In Christ,
Julie