Maybe with Tooway the peak to offpeak speed differences are larger.
What you need to do is find someone with one of the other services to see if it is better, before jumping. The install fee may not be the full £300 if they can re-use the dish, i.e. just need to realign the dish, and fill in the Ofcom paperwork.
The numbers using BET mean it is more experimental, and as it is pushing the limits of what is possible, then will always be a bit hit or miss. it is worth exploring.
If I was in your situation and unable to move, then I'd consider
1. Check nearest 3G mast, and whether a good external aerial will help
2. Order ADSL and even if it runs at 256Kbps, use it, as usage allowance is a lot cheaper than satellite
3. Can I get a wireless signal e.g. WiFi to another property and install a faster ADSL line there and relay it to my house.
4. Final last resort the satellite