Yeah that's what I thought as well. That's why I'm reluctant to buy ESPII or DDPR since I only have iPhone 4 so if I get the HD version it won't play smoothly, yet I'm planning to get iPhone 5 when it comes out so I want the HD version. I don't have problem double-dipping, but it's a shame to lose all my progress. Then 'Menneisyys' said it has GC which tracks all my achievements + hiscores and I was like, "so I can transfer my progress?" Guess he's wrong or misunderstood my question.
If you only want to beat the game once..not much replay value. If you want to chase high score, or beat the game without continuing or losing a life at higher difficulties, there's plenty of reply value. Each run for me take ~30 minutes..but you can select individual levels to play/practice. Cave games are meant to be replayed over and over to perfect your game. Deathsmiles has an iphone mode that has an "rpg-lite" element in collecting equipment for your "ship"/character. The items actually has different effects. To collect 100% of the items will take a while..so in that respect, Deathsmiles has additional reply value.
Hopefully this won't count as spam.. Recently, the Bullet Hell group had a discussion about which Cave games are each of our favorites. I've summarized the discussion in the following thread from the general discussion forum: Your favorite Shmup from Cave? Which is your favorite Game from Cave? Since the Cave sale is still on, hopefully this read can help people to decide which Cave game to pick up. =)