In general, most of the functionality provided by jsvc is provided by systemd, with the exception of opening of privileged ports (see below). If possible, it is a very good idea to switch to using systemd functionality directly, since things become simpler and more efficient.
Your unit file looks mostly OK, with the exception of
ExecStart=/opt/tomcat/bin/startup.sh
ExecStop=/opt/tomcat/bin/shutdown.sh
This part looks like another wrapper which can be replaced with a direct to
java -jar ....
Opening privileged sockets
Under Systemd this is usually done through socket activation. Systemd opens the socket and hands it to the daemon as an open file descriptor (like stdin, stdout, stderr).
The daemon can then be started as unprivileged user, and does not drop privileges itself. The daemon has to support this, and instead of opening the socket by itself, it should use the one it was given. Under Java this is made very problematic by the lack of support in the Java stdlib.
AFAIK, tomcat does not support socket activation, so if you want to use an privileged port and run the daemon under an unprivileged user, jsvc might still be necessary.