so i've thought a bit about the best place to post this, but i thought that this would be the most appropriate since i have done some tests, none of which are official because i don't have a BB-10 stadium.
i would like to give my initial thoughts on the new track SA165, of which i have 2.
in the "normal mode", where the concavity of the disk faces up, it allows the bey to wobble at large angles without scraping, however this was on a relatively flat surface. i'm not sure how the inclinations of a stadium would alter this property. some predicted that the bowl shape of this disk can give the blade a signifcant LAD advantage when almost out of stamina when the part came out, and it is true that once fallen on its side the blade is still able to make quite a few rotations lasting for approximately between 1-2 seconds (this was measured on a rubber sharp tip due to it easily tipping over at low spin velocities and having no LAD properties of its own)
in the "zero-g attack mode", where the concavity of the disk faces down, the small bumps around the rim of the disk come into contact with the surface of the stadium when tipped over, resulting in a greatly decreased LAD performance, although some still exists. that said, in this mode the angle of wobbling before the rim comes into contact with the stadium surface is greatly decreased, and hence presents a balance issue. however, it should be noted that tips with their own LAD properties such as RDF and WD can be used to completely prevent scraping within the natural sloping of the bottoms (i.e. the bey does not slant at angles further than the plane of the WD tip) on a flat surface, a WD tip completely lying on its plane will leave just over 1.0mm of space between the edge of the disk and the floor. again, this may decrease to a concerning amount in the curved nature of a stadium which i cannot vouch for.
i cannot draw any conclusions about the defensive properties of the track at this point in time, as it is rather difficult to get an attack type to hit full force on the defense custom i have tried to mess around with (MF-H Death Cygnus SA165 "zero-g attack" RDF) in a stadium as big as mine, not even taking into account that my stadium is broken. however, at low track heights (100) which allowed for flash to hit the plastic rim, the plastic-metal contact did reduce recoil. yet considering that low track attack customs seem to have fallen out of favor compared to their S130 and __145 variants, the chances of the aforementioned plastic on metal contact are really quite low.
one final point i almost forgot to add: not all metal wheels can utilize SA165 in both modes legally(?), due to the overhanging of some metal wheels (my death wheel, for example). in "normal mode", the wider part of the track is perfectly in line with where the metal wheel is held in place by the track. as such, metal wheels with an overhanging rim like death do not allow for the disk to be completely fitted on in normal attack mode, and hence a bottom cannot be fixed onto the track, creating an illegal situation. I tried screwing in the facebolt AFTER attaching a bottom to the track to prevent the disk from popping out in order to accomodate this extra overhang, and it did work aside from the fact that i nearly broke the facebolt and track from over tightening it. however, i believe this is illegal because it would change the overall height of the track and not let it serve its intended purpose.
overall, i feel that in normal mode SA165 has a potential as a stamina track due to it's LAD capabilities, although it's odd height might be its downfall (but TH170 is in the "competitive MFB combos" stamina list, and a i doubt a difference of 0.5mm would be much) it's wide diameter (although not as wide as BD145 i believe: i measured and both my SA165 have a diameter of 4.15cm -just short of the death metal wheel-, but i don't have a BD145 so hey, what do i know xD) and weight (??no scale so i can't measure..) may help it in the defense category. i do believe that it encounters less scraping problems than BD145, but since i don't have one i can't vouch.
that's all for now (oh wow, that was quite a bit O.o) but i hope members that have the parts (and a stadium.... curse me) can test for top-tier potential!