One of promised benefits of an ecosystem is choice. Microsoft often touts the ability of consumers to choose among multiple PCs — and smart phones — from multiple vendors as a differentiator between itself and Apple. In the Windows Phone space, however, there hasn’t been a whole lot of variety, in terms of features or price points with the first-generation of devices. The HTC Trophy 7, which will be availble in Verizon Wireless stores as of June 2, looks and feels like a number of the other Windows Phones on the market. The Dell Venue Pro is the most differentiated of the Windows Phones, but for now, Dell officials won’t say whether the company intends to offer a second generation of WP devices. And the Samsung Focus — the WP7 device with an AMOLED screen and extra-thin form factor? That device has been plagued, more than any of the other WP7s, with operating-system update issues that still have yet to be completely resolved. At the Computex show this week, Acer (one of Microsoft’s three newly announced phone OEMs) is previewing its first WP7 device, the Acer W4. From the early spec list (3.5-inch WVGA screen, 8 GB storage, 1 GHz Qualcomm processor), this looks to be just another Windows Phone. What’s disconcerting is the W4 is expected to be Acer’s first “Mango” phone. I’ve heard a number of Windows Phone backers tell those unimpressed by the first generation of WP hardware that Mango will change everything. New Windows Phones running Mango are expected to be in the market this fall, in time for holiday 2011 purchases.  But the Acer W4 doesn’t make a convincing case for the coming generation of Windows Phones. I’d expect Nokia — which is on track to get at least one of its first Mango WP7 devices out in calendar 2011 (according to its CEO Steven Elop) — will bring something new and different to the table. Hopefully, some of the other WP OEMs will have some new and different handsets that won’t be bogged down with carrier testing and will be available this year, too. But in the interim, the situation isn’t great for those open to a Windows Phone. One of my readers, who describes himself as a Windows Phone advocate who really likes the WP software, explained the dilemma: “I support many companies moving away from BlackBerry and BlackBerry servers but I can’t tell an exec to buy a bulky small screened phone or a large screened phone with a very short battery life. “While Microsoft may be promising more hardware providers when Mango is released, Microsoft has lost plenty of potential clients and with many companies; they have their employees stick to the 2 year policy on replacements of phones.”