Nice looking house!
I always ask about the movie aspect as many people are thinking 16:9 format HD rather than 2.39 or 2.35:1 CinemaScope and 1.85:1 Academy formats or the related higher resolution sources that are defined in te DCI and more likely to be part of actual digital cinemas. Nor is achieving the very low light levels, viewing angles, etc. associated with a digital cinema always practical in a multipurpose space.
One consideration may be that while "HD" is 16:9 format, typically either 1280x720 or 1920x1080 resolution, many common computer sources are 4:3, 5:4 or 16:10 format resolutions. It is usually no problem to show a 'narrower' format on a wider format projector, for example displaying a 4:3 image on a 16:9 native projector just leaves a black column down each side, which can probably be masked with your curtains if desired. Doing this may require some scaling, either in the projector or externally, for many common resolutions but that would primarily be upscaling. A more common issue is 16:10 format computer images versus 16:9 film images. If HD video is the primary source than a 1920x1080 native resolution projector may be the best choice. However, where computer images are the priority then my personal preference is to use a 1920x1200, 16:10 format projector as that allows direct display of 1920x1200 computer resolutions and full screen projection of any 16:10 computer resolutions while also supporting native 1920x1080 video with minimal letterboxing at the top and bottom.
The projector brightness might also be something to really think about. The Digital Cinema Initiative specifies a goal of 14ftL from the screen but that also assumes very low ambient light levels, levels that are often too low for other uses. Thus I typically try to get significantly greater image brightness off the screen, maybe 2 to 3 times that, for a multipurpose venue like yours where you do appear to have good ambient light control but likely have to support note taking during presentations, lighting of presenters on stage, etc. Assuming an approximately 900 to 1,000 square foot screen (40' width and 16:9 or 16:10 format) and a screen gain of 1.0, that would be a 12,600 to 14,000 lumen projector for digital cinema and a 25,000 to 40,000 lumen projector for multipurpose use. And that is not accounting for any losses due to lamp life or any lens losses. It is not that a lower output projector will not work, your current setup proves that, but at least in what you look at as a goal you may want to look at higher output projectors. Barco, Christie and Digital Projection all offer 1920x1080 native projectors rated 20,000 lumens and up while Digital Projection also has 1920x1200 native resolution models rated at 20,000 lumens or more.