>>399
I wish I was able to best answer that for you. All I can really say is Deep Crimson has definitely upped the game's difficulty and introduced more technical differences in battle. If story matters to you, you'll want to start with Burst, since Deep Crimson begins during the final stages of Burst. I'd say look up gameplay of each game and see if you'd like to jump in on Burst or wait for SK2, which as of right now is coming out in August to the US, Europe, and Australia
It is possible that Burst goes on sale before Deep Crimson comes out. I know the Burst was discounted the week before XSEED released Senran Kagura Shinovi Versus for the Vita last year
Personally, I think it's worth it because I enjoyed the gameplay, the music, and the characters. I still play some stages even after having finished the story over a year ago - the game lends itself to "pick up and play" since each stage only takes a few minutes.