I have a new Mitsi HD1000 projector that right now is sitting on a box projecting from the floor until I get it ceiling mounted (hopefully next week).

I will be running a 25' HDMI cable along with a 25' component cable from the projector behind the ceiling / wall to the rear of the room where my audio / video equipment will be.

Up to this point I had thought I would just have the installer bring the two cables out of a hole in the wall near the equipment and plug directly from those 25' cables into my equipment.

While shopping at Monoprice.com this morning I noticed that they have HDMI wall plates now. This would look much better and be very conveinent. However I am leery about adding any additional connectors in the line between the equipment and the projector. Especially with the tales I hear of some HDMI cables not working well. It seems they can be "glitchy".

Am I just being paranoid? Would there be no problem with this wall plate and also one for my component cable?

IMHO, as long as you used appropriate gauge cables for the length you're running, using the wall plates shouldn't introduce any problems, and will be much more convenient than cables coming out a hole in the wall.

I'm using a monoprice hdmi wallplate, and it works perfectly. I have two, just haven't installed the other yet. So far, so good. Marantz 7001 --> 33' monoprice hdmi cable --> Sony hs60. All hdmi cables are the cheapy monoprice ones...

Conventional wisdom is to avoid any connection you can in any path. I just redid my room and went with a junctiion box and a plate with a hole in it to run the cables into the ceiling and thus to the equipment bay. I think this looks much better than having any cable running between the projector and a wall plate even if it is just one foot long. Did the same thing with the power cable. Installed a plug in the attic and ran the power plug through the hole and plugged it in. Again much cleaner than having a folded power cable hanging behind the projector.

Murphy can step in at any time. I like to avoid him when I can.

I use a DVI wall plate in my dual-use "home theater" room (my projector is not permamently mounted). I saw absolutely no difference after I ran the cabling behind the wall and installed the plate compared to the original free run of cable straight to the projector. Typical use is running an SDI output from a DVD player into an iSCAN HD then 720p to a native 720p LCD projector. The output of the iSCAN HD does go through a Gefen DVI 1:2 splitter that also acts, as I recall, as a signal amplifier and may allow longer more stable runs than without this in the signal path (the other output of the splitter runs to a wall-mounted plasma in the workout room).

Probably about the same level of concern as using a high quality DVI/HDMI plug adapter.