Half-distance base or sweet spot base

Hi, newbie on here.
Am training for my first 70.3. Have just completed low volume half-distance base to get started. I still have, wait for, it 31 weeks (to Mallorca). Am thinking move to mid volume 1&2 sweet spot base for next 12 weeks then build and speciality for the next 16 (leaving three weeks for unforeseen stuff). OR should I stick with the half distance base and move up to Mid volume and do 1.5 8 week sections?
Will augment either with one or two longer rides a month outside to keep me ticking over on the road.

Overall looks like a solid plan, if you can accept the rather rapid increase in volume - SSB mid vol not just being a “volume upgrade” but also a program meant for pure cyclists. Adding run and swim workouts could be a shock.

Just like 70.3 tri base, SSB2 will introduce you to VO2max workouts at the end of the program. The only issue I have is that the final week of each sweet spot base period is “recovery on steroids” (i.e. zero medium to high intensity, easy spinning all week). I would assume you’ll have 5 spare weeks rather than 3.

Resist the temptation to repeat any of Build because it’ll kill you…

Thanks, most of my winter training will be on the bike. Will do proper base on the swimming as well, but minimal running to prevent old injuries. So am thinking cycling specific base will be ok. I guess if it’s too much I’ll go back down to low volume.
Yes seems like one build phase is more than enough!