No, the phone will not display anything other than the 3G symbol at the highest speed. That rumour is dumb.
If you're in an area without HSPA+, then ofcourse your phone won't have those speeds. There's tons of other factors to take into account as well. Also, keep in mind that Rogers HSPA+ can deliver a potential maximum of 21mbps, whereas the iPhone can only reach 14.4mbps max. While not full speed that Rogers could deliver, it's still double what the 3G speeds were. It could still potentially reach that maximum, meaning it is fully capable of working with Rogers HSPA+, but it probably never will reach maximum speed.
First off, those are ideal maximum speeds. You don't routinely get those and what tends to happen is people that don't just automatically get them start the rumours that the phone isn't capable of it.
Basically, symbol wise, HSPA and HSPA+ are teh same thing on the iphone, meaning that it will only display 3G when it gets to that because, really, it's teh same network being used for the speeds. The only difference is that the iPhone 4 (3GS and 3G too, maybe, I dunno) can only reach a maximum speed of 7.2mbps, even if the network was capable of giving 100mbps. It's just the limit of the hardware and that's all it can accomodate. The iphone 4S on the other hand using the same network (which is why it still only displays 3G) can only attain a maximum speed of 14.4mbps, even if the network was capable of giving 100mbps. It's like this terrible analogy: You can fill up a 1 cup measuring cup from your faucet. No matter how much you're pouring out of the faucet, that cup can ONLY hold 1 cup. You get a 2 cup measuring cup and it's still being fed form the same faucet, but it can ONLY hold 2 cups, even if you're pouring gallons and gallons of water into it.
The phone is capable of speeds up to 14.4mbps, but your network will probably never give those speeds. There's just how many people are online at the same time slowing down the network, there's network signal strength, there's the people that are online that might be stremaing or downloading content which will slow down the network, there could be an event in your area where thousands of people are texting all at the same time which is clogging the network, there's potentially limitless reasons why the network os bogged down or not delivering the speeds your phone is capable of. It doesn't mean the phone isn't capable of reaching those speeds, it just means the network is not delivering it. I suppose if every single cell phone user in your city all immediately dropped dead, then you stood next to the cell phone tower and used your phone, being the only user left would give you those 14.4mbps speeds, but short of that happening, you probably won't ever get them. You could, on the other hand, get the 7.2mbps or more realisitcally, because it's less than half what the network is capable of. Also keep in mind that unless you currently live in an area with HSPA+ coverage, you won't get anything faster than 7.2mbps max. (cause it's not country wide yet, there's still plenty of Rogers serviced areas that only have 3G still) http://www.rogers.com/web/content/wi...909-_-coverage