The gist I'm getting is 'there is a difference but how serious the dif. is requires us to find other ports to look at.'
Are we going to have to wait for Sonic Forces then to get a good read?
Even Sonic Forces is only going to be good for limited comparisons, as it's fairly technically reserved and was designed with the Switch in mind.
The real question is how will the Switch deal with games built to make effective use of the PS4 and X1's hardware. Stuff like The Witcher 3, Battlefield 1, RDR2, etc. Switch games have to be built with its portable mode as the baseline, and that widen the gap between it and the PS4/X1 to almost the size of a generation jump. None of those games are impossible on the Switch, even a PS2 could run TW3 with enough scaling, culling, and re-engineering, but its considerably more work than porting between the PS4, X1, and PC. The developers of such games have to think a port is really worth it to bother, which is likley why all the ports so far confirmed have been mid-tier (tech wise). Dragon Quest Heroes is probably the most demanding 3rd party title so far released on the Switch, and even the PS4 is considered fairly average.
If developers decide it's too much work, there's a chance we'll never see a genuinely demanding PS4/X1 title make its way to the Switch. I personally hope that's not the case though, as at minimum it'd make for interesting discussion.