I'm a first time user of Silverstripe and these sites were made over a very short period. I'm absolutely in love with Silverstripe, it's easy to use, with some really cool features. Good work guys and thanks heaps for your help on these tight deadlines :)
timewise, i think we had them both up and going in less than a wek (if my memory serves me correctly) but it did mean a 6am start this morning and (oh dear) working int hwe weekend ;) to get them up by 8am ;) the first bits took a while, being as it was m first into to ss at all, but once you figure out the $ you're away laughing. you can do anything with those $ things :)
When it comes to websites, Silverstripe is a pretty superior Opensource CMS, so it's the natural option.
When it came to developing a product like PlanHQ, we've made it from scratch so had the choice of using a whatever technology we wanted, and we met up with our lead dev Koz who's one of the lead guys with RoR so that made our mind up.
Developing a good product I still all about people and what they know, so If you've got good PHP developers then do the development in PHP, and consider SilverStripe as a platform. When it comes to websites, I want to grab a CMS that does plenty out of the box but can grow and be customised however you like, SilverStripe's positioned in this space perfectly.