s300 has secondary maps ability,the s100/200 dont.

if u do go down the hondata route,for the extent of the build ur planning,just go the extra yard now on the s300,u wont regret it,just make sure u dont use a jdm ecu for the base & u will have full boost control,so theres a coupla hundred bucks saved on electronic boost controller,all u need is like a $80 solenoid.

u'll more than likely spend less time on the dyno with the s300,so theres some more money saved.

onboard datalogging is great for troubleshooting little intermittent probs too,so even more money saved.the list goes on,more cash up front but it will gradually come back to u.

if u do a bit of research,some honda ecu's are boost capable as is,so just a matter of socketing the s300 in,but in the end its only about 4-5 relatively cheap components that have to be added to the ecu for boost control,so shouldnt cost too much extra to add.