Build whatever one will suit your volume needs as that is the only difference between the variations...aside from width where the "tube" versions are specifically designed to have all the bracing and tuning accommodated and still fit tube heads.
If you need 4 ohms minimum then you'll need two 8 ohm speakers...either together in one cab or two single cabs.
With regards to weight on top...I weigh 220 and not only can I stand on my 15/6 I can jump on it without worry. They may be light but they are structurally sound in every way.
A 1515/66 (or two 15/6 cabs) will crush an 810 in volume and CLEAN low end and will weigh significantly less. A single 15/6 is the equivalent of a 610 at full power handling, so any dual 15 will be like a 1210, only FAR better in the true low end.
If you need 4 ohms minimum then you'll need two 8 ohm speakers...either together in one cab or two single cabs.
With regards to weight on top...I weigh 220 and not only can I stand on my 15/6 I can jump on it without worry. They may be light but they are structurally sound in every way.
A 1515/66 (or two 15/6 cabs) will crush an 810 in volume and CLEAN low end and will weigh significantly less. A single 15/6 is the equivalent of a 610 at full power handling, so any dual 15 will be like a 1210, only FAR better in the true low end.