Hi Marcus,
If I were you, I’d definitely go down to whichever store near you has a Hero in stock, and have a play. While there’s some discussion about different versions of the handset and performance (anecdotally people are noting that black/grey models, such as are being tested in the US, aren’t impressing as much as their white counterparts, such as we tested, in the UK; HTC themselves say that the firmware was the same on all demo models) there’s also a fair chance that user expectation comes into it, so you may find the Hero simply too slow for how you believe a smartphone should perform.
Unfortunately I don’t still have the Hero to test with different microSD cards, and the card supplied was unmarked as to which class it was. If, as has been suggested, the Hero uses the memory card for a swap-file then there’s a possibility that switching to a faster microSD could improve performance. Again, without doing more testing I’m afraid I couldn’t say conclusively.
At the end of the day, the processor and RAM in the Hero aren’t ever going to change; the firmware, meanwhile, might. Personally, having tried all three of HTC’s Android phones, I wouldn’t go with anything but the Hero – the UI improvements are way ahead of the native Android build, and you can always turn them off if you really prefer the standard version – since I imagine that HTC will always be developing at the forefront of what Google make available (such as Donut).
If I were you, I’d go to my nearest store with a working demo unit, load up the Hero homescreen with widgets, start up some apps, browse to a few pages and just see how the phone performs. This is a subjective thing, frankly, and only you know whether the Hero’s performance would be a frustration or sufficient. Let us know how you get on :)
Chris