Honestly, I find with most competitive hobbies, it's expensive.
To do well, you have to spend money.
If someone cannot have access to the best, it simply means that they can't perform as well as their equal, who does.
To ask for the current hasbro stadiums to be legal is not to ask for a widening of the circle of beyblade, it's asking for a lowered standard.
If people with Hasbro stadiums wish to contribute, simply find combos that do well in one of your most balanced stadiums, and post it in the request thread.
A sub-forum is largely unneeded, as there are almost no new releases, no set release dates, and apart from a few parts, the difference between the brands is minimal, other than Hasbro beyblade's weight.
Honestly, if you argue the durability factor, if you abuse your TT or SonoKong beys enough to break them, chances are you'll break your Hasbro ones too.
The Hasbro stadium testing, "Top Tier Hasbro BMF Combos", Hasbro testing thread and the Metal Fusion/Metal Masters topic is enough IMO.
The Hasbro stadium testing thread can house all the testing for which stadium is most balanced, the Top Tier Hasbro BMF Combos thread can house the combos which perform best in Hasbro stadiums, and the Hasbro testing thread contains all the testing necessary to find out what's the best combos to use in Hasbro stadiums.
Meanwhile the Metal Fusion/Metal Masters thread is where all Hasbro release announcements go anyway.
What other gain could come from a Hasbro sub-forum?
EDIT: @LeoneTempest: I believe it has already been established a long time ago in one of your threads that the Lightning Force stadium is definitely not up to standard. I distinctly remember you acknowledging this after I had provided results.
Wouldn't that mean currently Hasbro's only viable stadium would be the MXS, which is still not as good as the attack stadium?
I do however believe that there should be some passing remark about certain parts with large weight differences, which would increase defence and/or lessen recoil.
Coupled with the fact that Kai-V brought up about the similarities in appearance of the Hasbro stadiums, it would mean only a very small margin of people would have access to the equipment needed for Hasbro testing anyway.