We have two Dyson's - one cordless - much lighter, and better than the old uprights.

As for the intercom - you need to decide when you would use it - I'd say you really need a big house for it to be any benefit.

I love whole house vacuums. I wouldn't bother with an intercom system, but maybe a large family in a large house would find it useful.

I'd get a good vacuum and a Roomba.

Cell phones nowadays take the place of an intercom.

I’ve had a central vacuum in two homes and I would absolutely not want to have a home without one if I had the choice. The first one we had installed in a new build and the second was retrofitted into an existing home. Either way is not too big of a project, although I did hire an electrician to do some part of the installation. I think we needed an additional outlet or something. All together it cost under $2,000. I love it.
Wouldn’t use an intercom. We just call each other on our cell.

Had to chuckle that "the old house" label applies to one from the 1990s!

Our house is big and had an intercom that we don't use. Instead either get a lot of good exercise wandering the house looking for each other or we use our cell phones. I say get rid of it.

I don't know much about whole house vacuums but I am a huge vacuum person and wonder what the HEPA factor is and how the ducts get cleaned. I love my Miele vacuum and would never part with it no matter what.

Following.

My SIL has a Roomba and loves it. My MIL had one (we all pitched in and got her one for Christmas) and she hated it and returned it as she felt like she couldn't be sure it got everything and moving chairs, etc. was still a PITA. I'm trying to decide what to do for our new build (Roomba vs whole house vs other kinds).

We love our whole house vacuum! I did the install myself (new house, 2006) and plumbed the vacuum exhaust to the outside via a dryer-style wall vent. (I had always wondered how much dirt/dust was recycled back into the house with a normal vacuum cleaner, so there is no question now, it all goes outside!) It would be fairly easy to remove your existing central vac power unit and replace with a new unit; a moderately capable DIYer would have no trouble doing it. You might need a few elbows/fittings (the inlet/outlet on our Beam unit is spaced a bit farther apart than yours), but that is all available on eBay at minimal cost, and all the piping assembles with PVC glue similar to assembling drain piping. Easy to do.