This was a topic I wanted to have a discussion regarding back from over a week ago and touched very lightly on in lemonguy's odd22 AAA thread...only for RATO to be AAA'd extremely shortly afterwards which further substantiated the argument.
Historically speaking, I feel like Death Piano has been viewed as the easier file given it was SDG'd by Dossar much earlier than any RATO scores were approaching SDGs. However, I feel DP's structure is extremely conducive with Dossar's skillset, and his ability to perform better on DP than RATO is an outlier compared to most high D7 or D8 players.
As the former staff member in charge of difficulty assessment, I was fine with RATO being rated one point above DP when most scores were still quite poor on both charts. It was theorized RATO's abysmal conversion leading to one frame jacks, single frame gaps in one hand trill dependent jumpstreaming sections, and tons of poorly placed pseudo-jumps within the 48th sections would make it significantly harder to approach AAA compared to DP. Simultaneously, several top tiers familiar with how much of a difference a good conversion makes for scoring on a hard file acknowledged RATO would have at least a small handful of scores approaching or hitting AAA if it had ever received frame fixes. RATO was very recently AAA'd, and while the conversion makes it much harder to accomplish, it certainly isn't impossible.
Looking at scoreboards alone, it's quite clear that more players struggle with scoring on DP compared to RATO.
RATO's top 15 scores are all contained within approximately 30 raw goods while DP's range begins to approach 70, and tapers off into 'very bad' a lot quicker than RATO does. They're vastly different files, and while DP's difficult sections hone in on a very specific skillset, it's a skill demonstrated less proficiently at top tier levels compared to 240bpm jumpstreaming and burst control.
Would like opinions from the community regarding this given they're both very popular files but I've felt their ratings should've been swapped for a while now and recent events only strengthened that.