In this shiur it was stated that one of the dangers of aliyah is that kids will go off the derech ["OTD"], as is very common in the Dati Leumi [Religious Zionist] world. The statistics are really very high. I have seen that is is an estimated 25 percent. That means that if you have 4 kids chances are one will go off. 8 kids - two. רחמנא ליצלן. It is hard to define who exactly is "off the derech" because they are countless levels of observance and non-observance but this is a HUUUGE problem.
It is ALSO a huuuuge problem in the Charedi world but there the numbers are lower [I have seen about 10 percent but since they have an average of close to ten kids that means close to one a family!!].
The reasons for this discrepancy are numerous. One is the army. A LOT of good kids go off the derech in the army, which is a very secular institution. Many others remain generally frum but lose their passion [which the Chazon Ish said - when asked by a person who said he would remain frum if he went to the army but not be as passionate - is יהרג ואל יעבור]. We are ALL products of our environment - especially younger people. Charedim only send their kids to the army if they are ALREADY OTD in the hope that at least the army will make more of a mentsch out of them. But no good, well behaved Charedi boy goes to the army [unless he is considerably older and needs to for parnassa reasons - you can't get many jobs without army service].
Another reason is that Dati Leumi kids go to university which also very often has a deleterious effect on religiosity. There is no YU equivalent in Israel [Machon Lev is the closest thing - and frankly, plenty of YU kids also have a serious religious yerida כיודע וכמפורסם]. Many of them go to Bar Ilan which is extremely problematic on many levels, one problem being they they present themselves as being a religious university but without going into details.... [As one well known educator in Israel is wont to say "Az, don't make me talk"].
A third reason is that most Dati Leumi kids have access to the Internet which is a big downer. No Charedi family lets their kids have smartphones or freely surf the Net. The Internet is a SOUL-ASSASSIN.
This is not to say that Charedi society is perfect. I share clothing with a critic of various aspects of the contemporary Charedi world [i.e. me]. They have many problems on many levels. And they have much to learn from the Dati Leumi world who make wonderful contributions to Torah and general society. But when it comes to kids going off vs. kids who remain pure, there is no contest. Not even close. That doesn't mean that one should necessarily be Charedi. But it should factor in to the decision what type of home to have. Raising children should also be a major consideration when deciding whether to make Aliyah.
In another shiur [on the same site] a rabbi challenged the assertion that one shouldn't make Aliyah because kids go off the derech [which incidentally is very, very common when the family comes when the kids are older]. He said that the reason kids go off the derech is [hold on tight because you might fall off your seat as I almost did] because their parents have university degrees and the kids are sent to schools where they are taught only Torah, so they get mixed messages and go off the derech, kiss girls, smoke on Shabbos and get tattoos. The solution [in his narrative] is that you send the kids to Bnei Akiva, to the army and college and everything will be just fine.
Of course, that is nonsense. Kids don't go off because their father went to college and they learn gemara most of the day. There are MANY reasons kids go off but that is not one of them.
I also don't think that it is religiously ideal for teenage boys and girls to hang out together on a constant basis [as this rabbi encourages]. Teenagers have pretty big yetzer hara's and they are really testing it when they come closest to what is hardest to resist. Does that keep them frummer??
A wonder.
Anyway - the bottom line is "הכל לשם שמים".
Living in Israel is a HUUUGE mitzva ["שקולה כנגד כל המצוות" like Chazal say] but there are also other mitzvos in the Torah that must be taken into account. One is parnassa [although for many it is much easier to make it in Israel because tuition is so much lower than in the States and in general it costs much less to live]. Another is the kids and how they will fare. Another is parents. Kibbud Av vi-eim is a HUUUUGE mitzva. Number 5 of the big ten. And the list goes on.
The BEST way is to come when you are young and start out here. That is generally the easiest. That is what I did. Came at age 15 for the year. I have done "the year" over 30 times.
הודו לה' כי טוב כי לעולם חסדו!!!!