If you download from multi host sources you get more with pro hense increased download speed depending on your sourses . I belive 10 instead of 8 for a DSL connection ..It depends on your speed, but if you have a slow connection speed you will not see much or any improvement with pro. Turbo charged connection is improved but ..well not HUGELY
If you connect as a leaf you connect to 5 Ultapeers instead of 3peed. This will help you get better results for rare files
Lastly $18.88 is a small amount to pay for a brilliant application and even if you do not get great improvements ..you will be happy to know you are contributing to development costs
To be clear the 18.88 does not entitle you to support for life .... just 6 months but a pro application will remain working indefinitely.
Lastly if you have problems running basic, upgrading t pro is not going to solve them
I hope