Simon, I'm pretty anal with the clean saws also. I'm a little easier on them and take a little more time to clean them when I'm done with them. Won't use them on pine. I do have some rough looking saws that I call "the rat patrol" that I don't fuss over. One more scuff mark is no big deal on any of them. The 42 will not see much use partly because it's so clean, but mostly because whenever I want to use that chassis, I'm going to grab one of the 242's. The 242 is noticeably quicker IMO.
The 45 is one of those "forgotten" chassis that few people talk about. Originated from Partner. Plastic, clamshell, (may even be the first one), so it's not cool. What it is though is very smooth. Anti-vibe way ahead of it's time. That 3 spring set up with the top one between the cylinder and the handle is pretty much the same as what we still see today; and they came out in the late 70's? Power on the 45 is between the 42 and 242. Muffler would be considered restricted on sites like this, but it's reasonably quiet. Don't always want a loud saw anyway.
In this area, 35-40 cc saws are occasional use/clean up saws. Some gals and older guys run them for firewood cutting due to the light weight and the spring assist starters that are on many of them. They can do a lot of work until the timber gets larger. Homeowner or pro, the starting point for most people who use a saw on a regular basis is 50cc. Timber is hard and can get big here. 55-60cc is common for homeowners. Serious and pro users are running 562's and 372's.