Can we assume this is a big step up for you?
Like Bose, others, OHM is a unique approach to sound, you love it, or not. Quality very good, haven't heard any OHM in years, but I would bet they sound good and well built. You already know they are customer orientated.
You heard them, impressed, and I think they might/could sound even better in your smaller room.
However, if buying used speakers, for your sized room, you have lots of affordable options.I would consider the LP's, if in good shape and your tastes a good part of the deal.
2500 lps? your tastes? pull random ones out, look clean, near virgin? It's a great way to learn about other music you might never buy/try. About 25lf shelving. You can cherry pick later, sell the rest so not too much space is needed.
I would try to get him to include the amps for the subs. Separate volume control of subs is good, especially moving to a smaller space.
Do you have TT and Vinyl of your own?
That TT, decent but nothing special, very old, is similar to the many direct drive ones, home version. Fully adjustable arm which is good. If you really get into vinyl you might upgrade in the future. But, accumulated grime and/or worn pivot, etc??
this simalar TT, new, $300.
https://www.dell.com/en-us/shop/accessories/apd/a9291057?mkwid=sZVd4VvX1&pcrid=289223374548&pdv=c&product=A9291057&pgrid=79656934065&pgrid=79656934065&ptaid=pla-793374613625&ptaid=pla-793374613625&VEN1=sZVd4VvX1~289223374548~901pdb6671~c~~A9291057~79656934065~pla-793374613625&VEN1=sZVd4VvX1~289223374548~901pdb6671~c~~A9291057~79656934065~pla-793374613625&cid=314477011&cid=314477011&lid=59673400075&lid=59673400075&dgc=st&dgc=st&dgseg=dhs&dgseg=dhs&acd=1230980731501410&acd=1230980731501410&st=&gclid=Cj0KCQiArdLvBRCrARIsAGhB_szheAS2BHmcJJEK3Jjiznn1_ag9GJSNupUw8n3l1DywtkKU1TEJR3caArD4EALw_wcB&VEN3=811405026575058466
His cartridge? Stylus good or worn? Stylus replaceable? Or just plan $200. to $300. for a new cartridge. You could move that to any TT. (or, you have an existing cartridge you like?) Above AT comes with a cartridge, sounds good, but it tracks 2.5g minimum, heavier than I like, so I changed mine to a Shure 97xe 1.25g. Surprisingly I like 97xebetter than Shure V Micro Ridge and better than AT Microline (I have both).
https://hifiheaven.net/shop/Shure-M97xE-Audiophile-Phono-Cartridge?language=en¤cy=USD&gclid=Cj0KCQiArdLvBRCrARIsAGhB_sz-VNPqw6dysoy6mnZ9yCv4YR8D5uT8In_xKLxhttMphTK8DwCj9VcaAhxyEALw_wcB
Some vinly sounded great, other not. If some sounded great, the stylus is likely properly aligned and not worn.
If properly aligned, vinyl sounds great based on the engineering of that content, not the reproducing equipment, so don't let those non-involving onews concern you.