I'd say don't worry about it too much, it all sounds like it's working fine. You could always sick up a button/piece of pasta through the wand and then the brushroll housing to check the air paths, but you would notice a blockage I think.
"As it's an investment that I wish to reek from for many more years to come. So I look after it' so it can look after my home in return!" Good idea, and it's the right way to treat a vacuum cleaner. The DC24 does have a reputation for wearing the motor out through general use though, so don't be surprised if it does fail one day, they only have a finite run time, same with the brushroll motor. Luckily the parts are not too expensive to replace. It's not like a Hoover from the 1940s that will run until the end of time sadly!
Unless you notice something moving the wand flap manually, I would just keep calm and carry on, and keep washing the filters, it's the best thing you can do! The pre motor filter (on top of the cyclone) likes going through the washing machine too, then dry it in the airing cupboard/on a radiator for a day, will be good as new!
If you wanted to be really OCD about it you could split the cyclone and check the foam gasket that sits between the two halves, they wear alot with the fine grit that passes through the cyclone. Mvacs sell it for under £4. But then, what you don't know won't hurt you etc, if it feels fine, and works fine, then it probably is fine!