First off, I changed my bulb over the weekend. And yes, I could tell that the new one is brighter. (but I hadn't noticed it dimming... the old one still looked fine, and I will save it for when my new one goes out.)...
But, over time there is a decrease in brightness. I had 2,200 hours on high on mine when I replaced it.
I only know about the HC1500. It is a VERY bright projector. When I was deciding on it, I looked at the "better" mitsi projector which had "more" brightness than the 1500... Except it didn't. It only cost twice as much, for less actual light...
Brightness "ratings" are a scam in the projector business. (did I just let the cat out of the bag?...). Seriously, I don't know how they come up with the lumens, as I have looked at a bunch, and ones that they say were twice what my HC1500 output looked noticeably darker than mine... So your best bet is to actually look at one for yourself if you can find one... Don't trust what they "say" the lumens are... I don't know about epsons, as I haven't even thought about projectors since I got mine. I'm totally happy with it. Especially since I put in a blue ray player. The picture quality is incredible.
IPT, Yeah, my fishtank (compact florescent bulbs 2-96 watt) is pretty bright. It usually kicks off about halfway through Friday night movies, as I have it on a timer. It does add light to the room (even though it is all the way in the back of my room). But, I don't like it super dark when I watch a movie... I like a little ambient light, and the fishtank does that well. It doesn't bother me at all.
It makes no difference on the brightness of my movie screen having the fishtank on. I can even run almost all the lights in my basement with no problem. The only issue is this time of year, when there is snow on the ground and the light coming into the basement from the sliding doors... That can wash out the image in the morning light. But, blinds fix that.
Goear. Speaker placement is key in any home theater. I like the way mine is open, as it accomidates way more people than a closed theater would, and I use the theater when doing other things in the basement (like the craft room, where you can see and hear it fine from all the way across the room) Or while playing pool... Or even in my woodworking shop across the way next to the bathroom. I can see the screen from my workbench, and I wear my headphones if the wife is upstairs and I don't want to bother her with the sound of my speakers.
I have one of my back speakers mounted on the side wall (where it drops down) on the open side, so it has proper placement, and from the theater seats... The sound is amazing.
I have never been disappointed to have it open instead of closed off. It is much more usable when you have plenty of room to do other tasks.
I even have a side business doing hand bindery projects for my families printing company.
And I get to use my theater when doing that!
As you can see I have all the lights on and it is no problem, (and that is with the old bulb...)