I have catch-all forwarding on my domains which forward everything to GMail.
This isn't always great because; spam email gets sent to your domain, your domain forwards it to GMail and GMail sees the spam emitting from your domains IP address rather than the original source, your sending IP will eventually have poor IP reputation as result.
Some hosts have server-side changes in place to try to counter this but with the growing rise of DMARC it's not really something that has sustainability and can bring about other issues in itself.
Some hosts also provide outbound filtering which will catch the spam and prevent it from being forwarded but it's not always bulletproof unfortunately.
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Self-hosting email is typically a bad idea for reasons such as
- Power + network uptime - loss of connectivity = emails likely to go undelivered to you and never seen again (Some sending servers will re-try but many don't these days)
- In a similar vein; monitoring - goes down, you need to fix it
- Most importantly - your residential (or even business IPs from typically residential providers) will be almost certainly be on blacklists already just for belonging to a residential ISP and your email may never make it to the recipients.
Finding a better provider than TSOHost would be the end goal. 500MB per package is ridiculously low, unless you mean quota per mailbox? In which case the same applies but can easily be increased probably just by asking them to switch it to "unlimited" which will let it utilize up to the total amount of storage of the cPanel account itself.
