The entire neck on an SG is accessible, whereas ernie ball 5 string bass on the Turser, they join at the 19th fret. The tradeoff is that you loose a little in terms of upper fret access, but you gain stability in the neck and the guitar doesn’t have the SG tendency for the headstock to head for the floor if you let go of the neck when you’re playing with the guitar strapped on.
One of these is the Ibanez Universe model, the model ernie ball 2223 that helped catapult the 7 string guitar into favor with contemporary metal guitarists. As a signature model for Steve Vai, this model comes in a variety of form factors and finishes, but all share the same lightning-fast playability and top notch construction to facilitate easy playing across the entire fret board, as well as great sound when played through your amplifier of choice.
Other manufacturers have also made 7 string guitars that are also of noteworthy quality. ESP guitars, another popular brand among metal players, have a variety of 7 string versions of their normal lineup of guitars. The Eclipse, Viper, and M-Series all have 7 string versions while still retaining the familiar profile and playing ability of their 6 string counterparts.