Well, I would notice.
The differences between the two molds are huge, imo. So much so, that I sold off my last two RHC sets last month, but still have 20+ THC sets in the collection. *
The THC mold offers these advantages:
- concentric outer circle that helps protects the edge from breakage
- smaller inlay area ('standard' inlay size) resulting in larger amount of surface contact area between chips
- more likely to contain high amounts of lead (most were manufactured prior to the clay formula changes to reduce lead content)
- heavier, with better feel, stacking, and sound characteristics due to all of the above
- THC chips can have textured and real shaped inlays
- used chips typically wear down with smooth rounded edges, due to high lead content and mold design features
The RHC mold offers these disadvantages:
- no protective outer circle, resulting in common breakage where the hats are close to the chip edge
- larger inlay area ('grand' inlay size, or worse) resulting in smaller amount of surface contact area between chips
- lighter weight due to lead-free clay formula used since 2007 (formula transitioned between 1999-2007)
- glossy inlay lamination with no real shaped inlays (only fake 'printed' shapes, usually with poor color-matching)
- used chips are typically nicked and flea-bitten, due to lead-free formula and the mold design flaw (some also claim that heavily used RHC chips feel like plastic)
So yes, they look different, feel different, sound and play differently, and wear differently. I would notice.

YMMV, so get samples. Lots of samples. Enough to shuffle and play around with, so you can make an informed decision on what really appeals to you, before you start shelling out big bucks for chips you eventually decide you don't really like.
I also would never intentionally build a mixed set containing both molds. It still tilts me to this day that my Aztar Caruthersville ($5) and PCA ($1) sets have a wayward RHC chips in the middle of their otherwise all-THC mold lineup -- I use the PCA $5 in my Aztar set, and the Aztar $1 in my PCA set. Doing so doesn't tilt me during play, and lets me sleep better at night.
*
Par-A-Dice, Casino Aztar Evansville, Aces Casino, Grand Victoria, Terrible's (all four sets), Oak Tree Casino, Good Luck Club, Double Down Saloon, Mesquite Star, Sunset Junction.... I sold all of those sets, primarily due to them being produced on the RHC mold. Not even great inlay designs, edge spots, or color combinations could overcome the underlying mold inadequacies, at least not to me. And there are lots of sets I did not purchase at all, due to them being on the RHC mold (Horseshoe Cleveland and Cincinnati being among the most recent, but there have been plenty of others I passed on, too).