I've been using Spooky for a year now. For the first 6 months I used the basic generator (~$200) and then got the Central plasma system.
I initially tried a GB4000 with handheld contacts and I think it works similarly to Spooky.
It's hard to get an unbiased comparison of machines as people invest a lot of time and money into whichever one they buy and they become emotionally attached.
You can check out the Rifing Lyme Facebook group - a lot of good info in the files section there. They are strongly biased towards the GB4000 though as that is what the moderator uses.
This book has a good testimonial of one woman's recovery with GB4000. It is short on details of the treatment protocol but is good for motivation:/www.amazon.com/Second-Chance-Beat-Chronic-Disease-ebook/dp/B0160IPQN6
She is actually willing to coach people that contact her for free (via her blog or the Rife Forums) if they are using a GB4000 which is what she uses.
The GB4000 has the best track record right now as it's been around for ~10 years, 5 years for MOPA plasma add on. However the 6 month old Spooky Central plasma system is less than 1/2 of what the GB4000 MOPA (plasma) costs - $1700 vs $4200.
Personally I think the Spooky Central is by far the most advanced system out there as it's all computer controlled. It's actually more powerful than the GB4000 with MOPA as you can change the carrier frequency to be a harmonic of the pathogen killing frequency. After a year of Rifing I am still only running it 20 mins once a week as the herxes can be very strong.
Rife is very effective at hitting microbes burrowed deep in the brain and bones that I've found other treatments don't touch. It's like a sniper rifle though, you have to know what to target. So it's good to use in combination with a broad spectrum treatment like herbs that may not penetrate into these spots as well.