Having been using contactless on the buses since as soon as capping was introduced a few weeks ago, I thought I'd share my experience here as I was initially very concerned that the need for an occasional chip and pin verification would make life difficult for me. I'm pleased to say, however, that as of yet I haven't encountered such a verification request, so it seems that so far the special non-chip-and-pin allowances island talked about in May do seem to be set up and working correctly. (This is for a Visa CPC with First Direct, for what it's worth.)
The card I've been using has with one exception only been used for bus travel; since the capping facility was enabled (prior to which I used an Oyster) I've made 47 bus journeys across 11 different days. Touching in has nearly always worked OK (just one touch was met with a red light, which rectified itself on a second touch), with no unfeasible requests to enter a PIN. Of particular interest was the fact that yesterday I made a small contactless transaction in Tesco, at which point I'd have expected to be asked to enter a PIN owing to all the previous contactless bus journeys, but I wasn't.
So, suffice it to say, so far I'm very pleased it seems my fears of being stranded in Crews Hill after the last bus of the day had left at 2pm owing to the need to find a cash machine were unfounded. (OK, Crews Hill does have a train station too
but that costs more.) My only complaint would be that reading a CPC feels like it takes about 1.5× longer than an Oyster does, which takes a bit of adjustment as I'm not someone who waves an Oyster near the reader as I walk past; I always stop to make sure it's accepted before continuing, so having formed a habit of pausing by the reader for just long enough I now need to adjust that habit to pause for a bit longer. Not a great crisis in the grand scheme of things!