Depending on the set you currently have, it may not even be displaying all of rec709. My old DLP was supposedly 12 bit but for Bluray and OTA my new 10 bit oled blows it away for color fidelity. I'm going back through and rewatching movies and playing games because it's like a brand new experience, and with a 4k source fuggetaboutit.
If the set you are considering will display close to 100% of P3 you most likely will be getting a big upgrade over your old set.
Here are a couple of CIE color coverage charts that might help you with your question.
According to the second chart what i find really/really sad about DCI-P3 color coverage of 46% of CIE is the fact that NTSC/PAL/SECAM analog color standards used from the 1950's until digital broadcasting standards were set in the 1990's already offered 47% CIE color coverage, which is a little wider than the vaunted and much anticipated DCI-P3 standards.
Color coverage for Rec.709, the current digital standard, offers only 34% CIE color coverage !
So, we went from 47% CIE color coverage from the 50's until the 90's, then we got 34% coverage from Rec.709 followed by 46% DCI-P3 CIE color coverage, and now we can only dream about that 67% coverage promised by Rec.2020 standards...