I did indeed ride the 3'6" lines while I was in Japan, in fact, most of my travels were over the "standard" (the Japanese standard guage is 3'6") lines in Japan, as they were the cheapest lines to ride on. I used the Seshen ju-hatchi kippu ("number 18 ticket") during my travels while on holliday (or "vacation" as we would say in the states) when the school was closed. The ju-hatchi kippu allows you to ride any JR (Japan Railways) train that is a regular, rapid or limited express train for 5 days (can be non-consecutive) for about 15,000 yen (or $150.00 USD) as opposed to the Akita "Komachi" shinkansen (which ran from where I was studying to Tokyo) which was about 12,000 yen (or $120.00 USD) one-way WITH the student discout.
The trains I rode on for the majority of my stay were of the 701 series trainsets as seen at the bottom of the page on the link below...
http://ts.sakura.ne.jp/~rokko1go/page_e ... nrec40.htm
I also rode on a DMU (Diesel Multiple Unit) trainset when I used to go visit my homestay family in the port city of Tsuchizaki (incidentally the site of the last mission of World War II), although I couln't tell you what type it was...
As for "tilt" trains, those were on the express trains, and except for my rides on the Akita Komachi and the Tokaido Hikari shinkansen trains, I never rode on one (I was a "bimubo daigakuse," or "poor college/university student, so I couldn't afford to ride the express trains, had to beg my folks for the cash to ride on the shinkansen!!!!), so unfortunately I can't tell you how well they performed. Although, for the most part I will say that the regular trains rode quite well. My only complaint would be of the Meitetsu (a private railway line that operates around Nagoya) EMU (Electric Multiple Unit) cars, which had horrendus transmissions or traction motors, which ground and screamed like banshees while getting up to speed. (But that's a minor issue)
I did, however, do some digging for you on the subject of the tilt trains, and found some examples of "pendulum" style express trains over there.
Here are some express sets built in the JNR (Japan National Railways - pre-1987) era...
http://ts.sakura.ne.jp/~rokko1go/page_e ... nrec30.htm
According to the author, the 381 series trainsets (third picture down from the top) were the first pendulum (or tilt) trains in Japan.
Here are some more modern express trains from the present JR (Japan Railways post-1987)
http://ts.sakura.ne.jp/~rokko1go/page_e ... nrec60.htm
And just for kicks and giggles, here is my namesake shinkanesn, the Akita "Komachi"...
(Although, the shinkansen run on the "broad" (at least for Japan!) guage of 4'8.5")
Hope the links help you out, David, enjoy!