If PingPlotter Free is showing a solid connection without packet loss or latency variations, then PingPlotter Standard is probably going to show a similar picture. The Standard edition will let you use TCP packets and specifically use the same port that SSH does, but *most* of the time we see a strong correlation between ICMP packets and TCP packets.
Another thing you can try to do to capture problems is to increase the frequency of samples - from the default 15 seconds between sample to 2.5 (or even 1) seconds between samples. This will sometimes catch failures that a 15 second sample rate is missing.
Your'e certainly welcome to download the Standard edition in 30 day free trial mode and give TCP packets a whirl, though, and see if you can capture a problem.
Best wishes,
Pete