A nail was polite enough to puncture a tyre in a groove rather than cause sidewall damage, and the TPMS alerted me to the low pressure before I could tell from the feel of the road. This was my first time using a repair kit, but I had looked it over ahead of time and knew what to expect. It was nice to not mess around with removing a tyre on the side of the road.
Kit use is straightforward, although it took a couple moments to realize that the 12v power outlet in the car is only energized when the car is powered on. The tyre pressure gauge quickly increased to over 40 psi and then dropped down to ~ 20 psi. Then it took a good 5 minutes to inch back up to 35 psi. I'm not sure if I over-inflated the tyre initially and caused more problem than necessary. After removal of the kit I could still hear air hissing out so I figured I would have to reinflate the tyre periodically on the way home but a pressure recheck after a couple of miles showed 35 psi and I could not hear any more leak so the repair improved with a bit of driving. The car tyre was repaired 4 days and about 25 miles later and still had 35 psi the day of repair.
Tyre repair was done at a 'Big O' tyre franchise. I brought them an OEM Denso replacement TPMS sensor bought off Ebay for $7 they were happy to install for free. This may not have been required but I didn't want to risk a faulty TPMS afterwards or be in a position of paying the store rate if they determined replacement was needed. The repair cost $19, the same as a puncture repair without sealant. The internet is chock full of stories that the tyre cannot be repaired after sealant is used but that was not my experience and the repair shop was not really burdened and other than thanking me for letting them know that sealant was in the tyre so that they did not make a mess, they did not seem to care. So far as I could see, the only extra step was washing out the sealant with a water hose.
I've yet to refurbish the kit. After use I tried to clean the hose and passages from sealant by running the compressor with only air but I don't know if that is enough. Next time I'll also run some water through the kit and hose when I get home. The replacement kit at Nissan is prohibitively expensive, but tirerack.com has the sealant and hose for $30 or I can buy just the sealant for around $20 on Ebay or buy (I think) the same kit but branded for a different car for under $20, e.g
http://www.ebay.com/itm/Brand-New-Origi ... 2536737861
All in all, this was anti-climatic and thankfully not an expensive melodrama. And as an added plus, my wife is now much more comfortable with the possibility of a tyre puncture while driving alone.