Looks fine,handy for ppl that want to pick & choose all their individual parts.
That stabiliser is a good idea & it doesn't necessarily have to be bolted through the frame...it can be clamped.
Better....dunno about that,the Grubee base is pretty good but it doesn't have that stabiliser idea(easy to fab though) & i wouldn't touch the cheaper all pressed-metal base that's available.
This Oz base seems strong/versatile & u can get the base quite low in the frame for better handling...also the Grubee is VERY hard to buy as a seperate item.
I'de buy the Oz base.