Skipping the UVB would save some money (up front, and operating costs, and UVB should be metered just like heat so add a Solarmeter), and not give up anything.
I have my BP in a 4 x 2 x 1 and it works pretty well. At the same time, more height would definitely be beneficial for all the reasons mentioned -- access, climbing. Also agree on the heat issue. Also, the T8 is quicker shipping (30 days, if the planets line up) whereas other sizes are normal lead times (18-34 weeks, though many reports say that is pretty optimistic). Tradeoffs.