I am sort of with you here,
Kill Devil Hill. Aside from Maiden, I really don't give enough music, enough of a listen, to be able to identify guitarists that well. But Maiden: all three are really very identifiable to me, from each other. Seriously, stop just listening to Adrian!
Couple of other observations. When you listen to SiT, if Davey drops some of his trademark
phrases (like those very quick, quick runs), he can sound very like Adrian. The
tone difference between them on SiT is very slight, I think. Therefore when their
styles meet, they are quite indistinguishable, at times. You could argue this was Adrian's influence on Dave, or perhaps more simply Dave staying closer to the material as written by Adrian. Either way, I've always found it interesting that Adrian never moved towards Dave's style, in any way. This could certainly be viewed both positively, or negatively.
After Adrian left, & it was Dave & Janick, it is also noticeable (as above) how Dave (again) moved closer to the other guitarists style. Again you could view this as a coming together of styles, or just Dave adapting --but again, if you remove identifying Dave by his
tone, his style can be quite indistinguishable (in the 90's albums) from Janick's, at times. I've heard other guys on the forum mention a previous discussion regarding Janick's influence on Dave.
Either way, it's quite interesting how in both cases Dave was influenced by the other guitarist, yet still (essentially) kept that trademark Dave style & tone, particularly live. I view this as a positive & perhaps as a counter argument to those (I've certainly said this) who say Dave hasn't really changed his playing style that much. I think in the studio, in some respects, he has. I've always (rather cynically) viewed this as Dave being able to play like the other two (because he can), with there being little evidence of the opposite: that either of them can play like Dave. I doubt this is the case, but have always wondered if Janick or Adrian really could do Dave's leads justice. This also nudges me towards viewing Dave as the technically better guitarist, perhaps unfairly (--on the other two.)
One last observation. Dave plays his leads using his neck (fretboard) pickup; Adrian uses his bridge pickup. (All guitars, obviously, have both pickups --but Dave switches to his neck pickup [as does Janick sometimes] for lead work.) I've seen it suggested that perhaps really early on (i.e. when Adrian joined Maiden) Dave & Adrian (deliberately, perhaps) decided to play this way (together) in order to have a tonal difference between them. I thought this was quite interesting if true.