I am also 5'8" and loved the 26" depth of the BPIAB (used it in my last birth). I couldn't afford anything close this time, but thought the 2" difference in this bigger fishy pool would work. Another 1-2 inches lower in the round pool would not be good enough for me. I suspected that it wouldn't be good enough, so I asked this question here last week, and got the advice that the bigger fishy pool would be fine (as far as hot water), and would work better for me than the round one with my height.
We could not get/keep the water hot in the BPIAB, but boiling some water on the stove worked fine.
So, we decided last week to go w/this fishy pool. I got a $5 coupon code for drugstore.com (just googled "coupon codes drugstore.com"), and they already have it on sale for $42 with free shipping. So, I got it for 37.99 total there, which is less than the round pool once you've paid for shipping. Thought that might help you with your decision.