Rav Feldman's speech in Baltimore as transcribed here by R. Yaakov Menken, has several factual errors that I feel need to be addressed. I must add a disclaimer that I am only going on what was written; I do not know what words Rav Feldman actually used.
1. He cites Rav Eliezer Melamed, Rosh Yeshiva of Har Bracha, as claiming that 20% of Hesder students cease religious observance during their army service. But Rav Melamed never said such a thing. What he actually said both here and here is that 20% (or more) of those who go through the Religious Zionist educational system through high school abandon religious observance. Rav Melamed also claims that the number of those who grew up in "Torani" communities and later cease observance is around 5%. Nowhere does he give numbers about Hesder students. A new survey of Hesder alumni had 7% of respondents describe themselves in categories other than "Dati" (Hiloni, Masorati, Non-Orthodox, non-denominational); however, this was a survey of Facebook respondents and hence non-scientific. Nonetheless, there is no evidence for Rav Feldman's rather staggering claim.
2. A second claim Rav Feldman makes is that "the Religious Zionist party" went from thirteen seats at the time of his moving to Israel to five today, and claims that "this is in no small part due to the secularization of their youth in the army." I don't know when Rav Feldman moved to Israel. At no point did the Mafdal have 13 seats. But the fact is that in the current Knesset, the Bayit HaYehudi party has twelve seats – up from seven seats in the previous Knesset (three Bayit HaYehudi/ Mafdal; four Ichud HaLeumi). It is strange that in a speech where R' Feldman is extremely critical of Naftali Bennett he seems to be unaware of Bennett's great political achievement. Moreover, it is incorrect to gauge the religiosity of the Religious Zionist population by the size of the Mafdal, and this is because of several factors:
a) In the years prior to Bennett's catapult of the Bayit HaYehudi, there was generally a right-wing party in addition to the Mafdal which competed for votes of the Religious Zionist population.
b) Religious Zionists have always been represented in other parties, and many never considered themselves obligated to vote for a sectoral party. This is a matter of political strategy and not an indication of secularization. The Likud, whose MKs are elected in primaries, have 4 Religious Zionist MKs out of a total of 20 (without Yisrael Beiteinu) – this is due in part to the large number of religious Likud members, and it is safe to assume that there are a large number of religious Likud voters.
c) There are many Sephardim who identify with religious Zionism and who made up a huge block of Mafdal voters before 1977, if not 1984, and now vote Shas due to the charisma and overall presence and authority of Rav Ovadiah.
All this being said, I fail to see how secularization in the army has drastically weakened Religious Zionist political strength.
3. Out of the seven indicted ministers to whom Rav Feldman points to prove the ethical bankruptcy of any non-Haredi educational system and weltanschauung, two are haredi ministers from Shas!
4. What I found most disturbing was the way the famous meeting between the Chazon Ish and Ben Gurion was related to this audience. R. Yaakov Menken claims that R. Feldman said that "Ben-Gurion went to visit the Chazon Ish to persuade him that religious Jews should be drafted into the Army. Ben-Gurion said that the state could not survive without it. The Chazon Ish countered that the Torah could not survive with it."
In fact, the Chazon Ish never said that it is forbidden to serve in the army, and the notion that he would have told Ben Gurion that the Torah could not survive if "religious Jews" were to serve in the army is patently ridiculous. Ben Gurion was quite ambivalent about his decision to exempt less than 400 Yeshiva students, and the notion that he would have held a discussion with the Chazon Ish about exempting the entire religious population from army service is also ridiculous. Moreover, "Peer Hador" – clearly a Haredi work – claims that the Chazon Ish was opposed to army exemptions being given to anyone who is not in Yeshiva, and quotes the Chazon Ish as saying that anyone took a Yeshiva deferment who isn't learning full time has the status of a rodef.
What is more disturbing, however is that there isn't a single account of the meeting, whether Haredi or not, that claims that the issue of the men's draft was ever brought up. Ben Gurion requested the meeting in the context of the struggle of the Haredi community against mandatory National Service for religious girls who were exempt from army service. But that issue wasn't brought up by either side either. Only the fundamental issue of how secular and Haredi Jews can coexist was discussed, without getting into any details regarding any part of the draft. (See Benjamin Brown's "The Hazon Ish", which deals with this episode as thoroughly as one can).
If one studies the surveys mentioned above about the Religious Zionist world and the Hesder system, they may come to the conclusion that there is a risk of secularization if one serves in the army; this may give Rav Feldman enough information to justify his position, albeit from a Haredi perspective. The Haredim as a whole clearly have different priorities than the religious Zionist community, and they aren't willing to risk their way of life in any way for the sake of doing military service. I fail to understand why this approach cannot be justified to Haredi communities without giving faulty information about other Jews and falsifying accounts of Gedolei Yisrael.