Downside of running own VPN server

I'm setting up a VPN server running on a Raspberry Pi for my family to use when out and about and using public Wi-Fi hotspots.

However, it's just occurred to me that with my 24Mb/1Mb Broadband, any traffic going through it is going to be bottlenecked by having to upload back to them at 1Mb!

So is it pointless doing this? At the moment, whilst I'm setting it up, I've got them using SurfEasy VPN, which is free for 500MB/month and that's probably more than they'll need anyway but I figured it would be more secure/private to use my own VPN server. Apparently they don't restrict bandwidth but I don't know what this translates to in actual speeds and whether they'd actually be better than my 1Mb or if the public WiFi hotspot is going to restrict the speed to each user anyway (say they have 24Mb but 24 current users), so that my 1Mb won't actually be a bottleneck.