Hi Walter!
I'm not sure about the shops you've been in, Rob, but most places carry a full range of display models, which customers are welcome to try out. Try asking a member of staff - they're trying to make a sale, and should be more than happy to help. Whenever I go into my local Comet or Currys, which is rather often, the display Dysons are full of dirt from where prospective customers have pushed them around the shop-floor before buying. It's always quite amusing - and enlightening - to watch them from a distance, and hear their comments as they form initial impressions of the machine.
As for the DC24's reliability, I can only second Which? Magazine's advice: Dyson have a below-average record for reliability, but are fully covered by a 5 year guarantee, so they're happy to recommend them as Best Buy models. I wonder if the 'poor reliability' record is unfairly weighted against Dyson; since 1 in 3 British homes own a Dyson cleaner (the other 2 owning 'Other', encompassing all other brands on the marketplace), people are statistically more likely to have had a bad experience with Dyson than with anything else!
As far as 'efficient' goes, I'm happy with the performance of mine, although if I'd been buying a cleaner sensibly, rather than for the novelty value, I'd have gone for the full-size DC25. Which? recommend both models as best buys. It's good on hard floors and carpets, but the hose is very short, and the tool they provide is just silly - so not a great choice if you're going to use it for stairs etc.
Here's a hilarious video of Sir James Dyson, Britain's 37th richest man/Knight of the Realm running his own durability test on an ill-favoured DC24. Note the pink Cyclon, the 'Dyson Model O', in the background!
http://www.crunchgear.com/2008/06/25/video-james-dyson-runs-his-own-durability-test-on-a-dc24/