Having had both think as far as noticeable use there is NO difference. Several years bac I purchased a Remington XR-100 in 204 and at that time 204 brass was as easy to find as Unicorns. Purchased a 20 Practical reamer as I had 500 rounds of 223 Dakota (Lapua) brass.
The rifle served me well then it was stolen,after looking for a replacement I found a AS New XR-100 in 204 now that 204 brass is readily available it serves the purpose.
Both of these rifles would shoot .3 groups with the 204 having about 100 FPS more velocity on paper there was no measurable difference as I have targets to verify.
From a Resale point the 204 is by far the better choice as factory ammo is available
Good Luck
Jim
