19 guilds cleared at least 5/6 HC, 4 of those are 10m. That pretty much shows where hardcore raiding is concentrated - yes in 25 m bracket. In 10m bracket the 2nd best guild cleared 6/6HC 3 days after Paragon, while in 25m guilds cleared it within 12 hours. That pretty much shows that there was limited level of hardcore raiding in 10m untill Paragon came and bring that hardcoreness from 25m.
Most of the posts do not mention why Paragon is raiding in 10m bracket. As far as I know, they lost some raiders and could not recruite new people with sufficient level of gameplay. Instead pushing on recruiting/merging they decided to go easier way, downgrade to 10 m but bring all aspect of 25 m hardcore raiding to 10 m bracket.
Paragon is not raiding 10 willingly, if they could they would have raided 25m. So I do not reckon their 10m kill as legitimate world first, my opinion. If they want to race, be it in 25m or leave it. 25m and 10m is not one race.