No ... it's kinda 6 one way, half a dozen the other. With a regular transom, I like the combination of a mechanical / epoxy connection. The slots in the transom create additional wood/epoxy surface. For your extended transom and it's narrow transom at the center (almost like a bracket), I'm not sure I'd cut the slots either. What I would consider however, would be silicon bronze large screws (#12 or bigger) run through the outside of your transom into the ends of the stringers as a back-up mechanical connection. Might keep things together if you hit a fishing wier, runaway deadhead log, or buoy some night! If you lag or big-screw through the transom into the ends of the stringers, predrill and countersink so the installed screw is just below the surface, and don't feel bad about burying it under epoxy and glass. Silicon bronze doesn't corrode from any residual wood moisture, and they don't swell up if they do. Run the screws at opposing angles ... top one angled downward, bottom one angled upward - 2 screws/lags is enough. Also, use nice large fillets with milled glass fiber on the inside and glass well - you already know all that.
Brian
