The mineral patches being at the bottom actually help in the beginning due to not having to walk all the way up to their patch (and also, workers usually prefer to return minerals/gas to the center-bottom part of their main building, further accelerating their income).

Despite this, I was still able to easily snipe most buildings with tanks and two nukes were able to one shot the nexus from the safety of their base. Assuming my map doesn't get approved (was never expecting it to), perhaps we can simply stretch the middle bases downward or the top left/right bases upward--or, if we compromise each base, they'd each only have to lose 1/2 - 3/4s of a supply depot in vertical units.

A more realistic and applicable suggestion I have would be splitting the 50 stacked minerals into 25 stacks (one stack near the top and the other near the bottom). This would make those game-ending scarabs or tank drops a bit less frustrating. I'm also under the impression that workers split into 25 stacks versus 50 would actually result in a higher income--if dispersed properly--due to the wandering worker glitch (only applicable prior to workers finding their designated patch I believe). This isn't at all play-tested but I'd happily run 10 simulations with each race to determine it's validity.

And lastly, I'd personally enjoy seeing the middle terrain become a bit nerfed, at least around the outside of chokes. Low money maps are constantly tinkering with terrain that's build-able on and terrain that isn't and it makes for exciting shifts in meta. Perhaps just enough terrain to fit a few missile turrets or a proxy robo, so aggression isn't deterred, but 16 gates in the center rallying into your base is sometimes a bit overwhelming. Bear in mind I'm a map maker and watch every KSL/ASL but I'm still far from a player who would be considered good.

(P.S. my files were too large to attach, but it's easy to glance at the distance and see it's a siege tank's wet dream)