DIY Graphene and PT15 share a lot of common traits, so yes, I'll say they are much more like sidegrade of each other than upgrade
Compared to PT15 / DIY Graphene, Nameless is tuned a littler smoother overall. But as far as overall sound quality goes, they are more or less at around the same level. Nameless is mainly a more relaxing earbud to listen to while PT15 / DIY Graphene are more aggressive i, their presentation.
All three are decent for Classical, through I won't say anyone of them can be considered as a Classical specialist. I am more inclined to recommend you to spend a little bit more for VX Pro instead.
how does the graphene's tuning, soundstage and resolution compared to the VX Pro? i already have the VX and PT15, so i think we can use them as point of reference