I got Samplitude bundle too last year. Don't know if I'll update to X4 or not. I like the program but don't know if the price for upgrade is worth it to me. SO3 I got too but never registered it, I used the demo.
Finally registered it and got X4 upgrade for free. Just getting into the program and I love the arranger and mastering section. Plus several other programs I brought. Still CBB seems like it will be my #1 DAW with learning Samplitude and SO4 for backup. SO4 might get the nod in the future if I get one of there control surfaces. I here it integrates with SO4 really well.