So I thought I would take the SB plunge. The POTs seem much more like the girl next door, while to many SA POTs seem very glammed up, They could even be a Boris and Natasha sting job.

Any luck with crypto on this site?

SB = Secret Benefits

I bought my credits quite a while ago and don't remember needing to  use bitcoin.  On their purchase page they list credit cards as accepted.  I didn't click further down to purchase credits as I still have plenty so I don't know what the lower layers reveal.  

Recently purchased credits on SB for the first time and simply used a credit card, no problem.  My success rate on SB is zero, but that's another story.

I hate the credit system, seems way too much like Ashley Madison where they were all fake accounts.

There may be fake accounts.  But I was on Ashley Madison and Secret Benefits has far more verifiably real accounts than Ashley ever had, at least as far as I could tell.  I never met anyone off of Ashley.  Checking my records I see I've met at least 14 ladies listed on SB.
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I've been thinking about trying SB as like many here, I had issues on SA with BS suspensions (been on there since 2016, I know what not to say on-platform) and got sick of their horrible support responses and did a chargeback (which, FYI, they didn't even fight).  I'd be interested to hear any current feed back from experienced members here.  I am back on SA (unpaid) and see a few POTs on both platforms, but none that I've met or even conversed with previously.

I know some people have used it successfully but it's been zero for me so far. I had one M&G and a couple of conversations that fizzled out. I'd say the response rate is lower than SA and there are some things to watch for that eat up your credits quickly.
There are a number of auto-generated messages -- it seems like the platform does this (if the girl doesn't click correctly) so I get several lines that seem canned, and nothing when I reply back. The same for "unlocking" pictures. Not clear why, but sometimes I will send a message and the gal will instead of responding, unlock those photos (usually nothing special) so you use more credits.. and then nothing.
It's hard to know who is genuine, but probably best to concentrate on the ones that view your profile AND/OR favorite you AND/OR send a message.

There enough variety from SA to be worth it?  How much are you spending to get to actual SB part in comparison to a month or two on SA then taking a break.

Do NOT spend credits on additional photos.  Get her contact info for the credits you spend to read and reply to her.  Then get photos that way -- they can send you photos via the app or via your text or email etc.  

I'd say Seeking is bad at having first day sign ups sending me messages.  I get a lot of first day messages.  Of course you can't tell on Secret Benefits since it doesn't give their sign up day.  
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Of course if you are paid up on Seeking, it doesn't cost anything to follow up on these first day messages.  Whereas SB requires you to pay to contact someone the first time.  
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I would say use SB if you want to keep your toes in the pool but aren't looking to make quick kills.  You can scope out the candidates at leisure with no pressure to close the deal in 30 days.  As I mentioned, I've met 14 from SB over a few years time.  
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If you want a tsunami of options, then Seeking is probably richer ground for that.  But you have to strike fast and often before your months are up.