John I just did my whole bus with Custom & commercial, for me it was between C&C and the west coast ones buying through Rackhams of Ipswich. I wasn't bothered who I bought off, I was more worried about who was selling the better quality. The price was with in a tenner of each other when I got a quote. I decided to go with c&c because I knew they would get them out quickly, but if I was doing it again and not in a hurry I would try rackhams.
The C&C ones are bloody tight and took a full day for me and one of my guys from work to do the whole bus.
I ended up getting one of the west coast front windscreen seals so I could compare and it went in a lot easier and looked good quality too. My main concern was the 1/4 lights, the C&C 1/4 light seals were a nightmare to fit, really really tight. To get the glass to shut we had to heat the rubbers up once installed with a heat gun and lots of G clamps to nip every thing up, each 1/4 light took 30 mins to get the glass to shut and seal as it should.
Although the C&C seals were difficult to fit the tightness does mean they seal up really well which is obviously the most important thing!