I'm trying to help my sister come up into the Smartphone world. I have a budget of $300 with which to get the best phone I can. She is on Telecom XT, so the phone must support that. She also is definitely technically minded, so don't bother suggesting any phones that "are a cracker once you install <insert custom rom>". 

I was initially quite keen on the Huawei Ascend G300 for her, which I can get for $299 from a few retailers (and some a little cheaper). But this is the Vodafone variant, and doesn't have both 850/2100 support. My daughter has an X5, and I'm quite impressed with that handset. If it wasn't for the frequency issue, this would've been my pick. I've tried finding a version that does support XT, but haven't had any luck so far.

I note today that The Warehouse have the XT variant of the Motorola Defy available for $249, but I've heard reports that it may be a little laggy unless you install a custom ROM. Anyone know how bad this problem actually is.

Finally, any other phones I should be considering.