I am one of the biggest buyers for buying groups, I have done millions in transactions and have sent to every group there is over the past 3 years. Most buying groups are okay, some scan in slower than others, some pay slower than others - most will lose a few packages over the year. You can research and find which are better for you.
However there is a bigger problem now with Amazon itself. Amazon in the past has been great with any problems always ready with a refund for lost packages even if it was thousands of dollars. Lately Amazon has clamped down and has tagged these buying groups addresses in their systems as "freight forwarder" and now no longer will fix any problem you have whatsoever. Doesn't matter what the problem is, even if it shows the package was never delivered, amazon will not help you in any way. Their copy and paste response will always be "this item was sent to a freight forwarder and we're unable to replace or refund the item. We recommend contacting your freight forwarder for more details, as we don't have any more insight or information regarding this matter, For more information about sending items via freight forwarders, please visit our Help Pages:
https://www.amazon.com/gp/help/customer/display.html?nodeId=201117950." As well the amazon drivers either must know this or have been increasingly bad at delivering packages because the numbers of packages missing has gone up astronomically. Previously you would have very few packages missing, now the past 3 months I have had 59 "lost" packages. I now have over $15,000 of loses and some guy in Delaware is probably living the life with all the stuff he stole from me. I will survive, I have made a lot more than $15,000 over the years however just a warning to others here that things are not as they used to be and it really is no longer worth doing buring groups with all the loses piling up