Am I right in thinking that the SIM free unlocked versions direct from Dell only support 3G speeds and it is only carrier specific versions that support HSDPA (3.5G) speeds?

If so then this is unbelievable. I have had several windows phones and all supported HSDPA no matter which carrier's SIM card I inserted (O2, Vodafone, T-Mobile etc). Surely Dell aren't going to penalise customers for buying a more expensive handset direct from them?