Topre actuation point and travel distance (HHKB Pro Type S)

[Flaubertt]

Hello!! Thanks to your awesome advice from another thread, I THINK I'm totally settled on a HHKB Pro JP Type S. However, I'm also going to be receiving a Filco Minila (with Browns), which I plan on equipping  with double 0.2mm 40A O-rings (the red ones from WASD). It's not only the 'mushiness', but also the reduced travel distance that appeals to me. Now, this is what I know about Browns and Topres (please correct me if I'm wrong):

Cherry MX Brown
total travel distance: 4mm
actuation point: 2mm
pressure bump: ~1.2mm
force: 45g
http://i.stack.imgur.com/CQoxi.png

HHKB Topre Type S
total travel distance: 3.8mm
actuation point: ??
pressure bump: ??
force: 45g
http://www.pfu.fujitsu.com/direct/hhkb/detail_hhkb-pro-jp-types.html

HHKB Topre
total travel distance: 4mm
actuation point: ??
pressure bump: ??
force: 45g
http://www.pfu.fujitsu.com/direct/hhkb/detail_hhkb-pro-jp.html

Now, which leads me to some questions:

1. Is it possible to buy more Topre O-rings (or whatever they are) and install them on the HHKB Pro JP Type S for more mushiness and even less travel distance?
2. What is the actuation point for HHKB Topres?
3. Is there a pressure bump for Topres? Is it more noticeable than for Browns?

Kind regards!

[daerid]

1. Yes. You can soften the landing and even apply o-rings to the up-stroke of the keys for a home-made Type-S style mod. Somebody on these forums has posted a how-to on that (can't remember where it is at the moment).
2. Generally Topre switches actuate at around the half-way point. The tolerances are a bit higher than for some other switches due to the capacitive nature of the switch (the switch actuates due to the change of capacitance of a conical spring under the switch as it's compressed).
3. Yes. All Topres have a tactile bump (some might argue that 30g do not, but in theory it should still have one) right at the top of the stroke. This is created by the resistance of the rubber cup as it's pressed. After a threshold is reached, the cup collapses rather rapidly. This makes it almost impossible to avoid bottoming out on a Topre switch in normal use (some can do it with concentration, and again 30g Topres are apparently easier to avoid bottoming out on).

[Flaubertt]

Well those are good news. I'm wondering if someone knows a website where I can buy O-rings for HHKB Topres? (Is that even how they're called?)

edit: by the way, daerid, thank you so much for your reply!