So your current setup is MORE then adequate to send thousands of messages per day with GSA. You do Not need a VPS.
However I would recommend to check your DNS as that could be a bottleneck. I use google public dns and its works great, but there are others, but your local ISP may have dog slow DNS, which is typically true of cable providers in the USA for example, where as phone providers that sell internet often have wicked fast dns, in the US. But thats just an example.
You could send 10K messages a day with your setup.
Captcha breaker will improve your success rates to be sure, but you might get like 50% success on a good list, like if you bought the lists I sell in my sig, then those are prequalified and you might get 50%to60% success with no captcha.
Then if you add on gsa captcha breaker you might pickup another 10% to15% or maybe a bit more increase in success.
Then if you buy recaptcha solving from a service, you will pickup another chunk of success but you are not going to get to 100% generally speaking because there are just too many variables. But each layer you add increases success.
Now if your just loading a bunch of keywords and letting gsa website contact do the scraping and the posting, you can do 1K submission per day but your success rate will be way lower, means it will just take longer.
But you have Scrapebox, so I would - and I do - use scrapebox to do all the scraping and then load the urls into website contact for posting.
