However in-ceilings scare me.
No need to be scared, they aren't that dangerous unless you forget to tighten them down.
I help my clients (builders, theatre designers, security and low voltage installers)plan installs with both bi/di pole in and on wall models as well as in-ceiling speakers every day. In ceiling speakers have become the most common for surrounds and even rears these days, especially with new homes incorporating great-rooms with nowhere to place rears.
Most DECENT in-ceiling manufacturer's build a 'fixed' angle in ceiling speaker, this means no mechanical movement, some make speakers that drop out from the ceiling, which LOOKs nice but reduces rigidity.
In my case, once again, I work with RBH products. They make a fixed in ceiling (in various grades,a polypro builder series, fibreglass or aluminum cones) all with high end 2nd order crossovers, swivel tweets, 3dB+/- treble and bass contour etc.
They are backed by a 25 YEAR warranty!! (yes you read that right)
One key with inceiling speakers that are fixed angle (allowing you to direct woofer as well as tweeter) is that they need ot be a larger diameter than the standadr downward firing models. If not, the plastic casing will impede the sound.
Here's a look at what I mean,
http://rbhsound.com/mc615l.shtml
This particular model sells around $ 325.00/pr + installation and they are pretty hard to find. No retail or online sales, so if you want RBH you have to find a local theatre installer, home builder/rennovator etc.
You can always email RBH and they will hook you up with alocal reseller/installer too.
Other recommended in-ceiling brands would be Speakercraft, PSB is OKAY for architectural speakers but are way overpriced compared to the equivalent product from other companies. Destination audio makes a good in-wall, DA is a little sister company owned by RBH also, they can ususally be found online too and at least offer 10 year warranty, though not quite to the RH standard they are a safe compromise.
The thing with RBH and related products, they don't spend money on marketing, advertising, showrooms etc. and deal directly with installers so the margins don't get inflated like Paradign or Klipsch etc wher the retailers bump prices way up and then offer partial discounts. This plus being an OEM, allows RBH to offer e better value fo rmoney than others, high-fi at mid-fi prices.
Anyway, there's 2 cents for ya, or maybe a quarter anyway