My DD travels from the same sort of area - there are a group of 4 who meet at Harrow on the Hill (coming from both branches of the Met line) and travel together. I think they quite enjoy the travel and it hasn't been too much of an issue. While you may not find large numbers, I think every year there are probably similar numbers, and as parents we all did actively collude to get them travelling together which has continued. We actually started CLSG in 2020, so there were no travel buddies etc., so for a few weeks we parents would take them to school to get used to things (as in we made a rota, so just one parent accompanying them all). However, I believe that changed, and the school do try and pair you with someone from a similar location.
The school was our first choice, and when considering other similar schools in terms of selectivity, ranking etc., we didn't think the actual commute time would be that different to other schools - the difference being, with the other schools, you are likely to have the security and comfort of the school coach vs. the tube. That said, there have never been any untoward incidents so it has been fine. I can only think of a handful of times, when delays have impacted the commute, but I don't think they have ever reached school after 9:30am, and that is 2 or 3 times over a 2 and half year period. During strikes, it is nearly impossible to get to school, but this seems to impact more than 50% of the class, even those who live closer.
A couple of considerations - initially I thought due to the commute, she wouldn't do too much after school activities, but that has not been the case - 3 out of 5 days she is involved in some activity, so that adds an extra hour to the day - and in those cases, can't always guarantee that the same travel group will be together. Again hasn't been issue - usually there's someone who travels to Baker St, or maybe Finchley Road, but she does travel alone from there at times.
This extra hour also has an impact on homework, bedtime etc. The pace does pick up in year 8, with regular tests in addition to homework - out of space but happy to answer any other questions.