I'm not sure this will help you.
I have never used fce, I have never used iMovie. I opened iMovie for the first time ever about 6 months ago - too weird and closed it after about 15 mins.
I have used fcp since 1.5 and am familiar/comfortble/profficient with it. I used to be full-time in video editing/camera/production but not all that busy in that area for a couple of years.
I am not going to install fcpx 'til it's fixed or at least until there's a clear sign that Apple are going to reinstate the missing features from Fcp 7. Heck why bother to learn it if they don't reinstate them - it'll become some ******* child of the editing world. No use in a production environment.
AAPL look like they're trying to reinvent the wheel with this release - and reposition the product altogether.
I'll wait until it becomes clear - because I can. Other users will not want to wait and have to move to whatever tool works for them in their workflow.
It may be perfect for you.
It is difficult to count on future releases of any program meeting expectations, and the way that Apple has been managing this release may be one indication of intent to abandon the true "pro" market altogether. Treat your work well, regardless of hobbyist or prosumer status. You never know where it will take you. Adobe Premiere is pretty good, and even Premiere Elements can be a cost effective introduction to an application that really does promise pro features. Even better, though... this might be a good time for users to familiarize themselves with Avid, if they can afford it. It's industry standard pro.
I don't think it's a good idea to spend money on the assumption that necessary features will eventually be added, especially when that assumption is based on rumor. It's better to purchase it when it actually meets your needs.
P.S. You can change the scratch disk when you create an event or use the File > Move Event command to change the location of an existing one.
I think you should buy Premier CS5 or Avid. It seems that Apple brand is not worth of any trust. The have just shut down Final Cut Pro and replaced it with iMovie Pro. It can happen with any Apple soft now. They can just shut it down and your money would gone for ever. They don't care about users who invested in their products. They just closing the product and that's it.
So if you buy this FCPX(press) you can find out next year that the soft no longer exist and have no more support.
I had actually used an Avid NLE program a dozen years ago, which was part of the software bundle of my purchase of an Apple G-3 "All-In-One" (Artemis)--with RCA jack inputs!--marketed to educators. That machine was the catalyst for my interest in editing video.
I'd been drawn to FCPRO because of the ability to do multi-cam editing; it provided a view similar to what a director would see in a "live" broadcast. Do you know if either of the Avid or Adobe products includes this feature?
I know there already exists a Piero plug-in that can be used with FCE which can sorta emulate this feature.