First: I feel your issues were definitely dealer related, as both of my local Massey dealers are stellar. The local Kubota dealer, while way overpriced on everything on their lot, is also good. I've heard people complain also about their Kubota, John Deere, NH, etc... Dealers also, and went to other brands because of it. It's unfortunate that you experienced a less than adequate dealer experience.
Second: Your MF machines were not typical of Iseki built Massey quality. Especially your Tafe built machine, which is well known to be problematic, and unfortunately, a bit of pre-purchase research may have been able to reveal that.... Unfortunately, that led you to experience the above dealer deficiencies.
Third: You are correct that your non-Iseki Massey units were not the "same quality" as Kubota. But then, in my experience with two new Iseki-Massey's and three new Kubota machines, the Kubota's haven't been up to the same quality level as my Massey's.
I certainly don't think that Kubota machines aren't quality builds, but it's not accurate for you to blanket statement that MF is not Kubota quality, unless you preface it more specifically.