Hi @theoretic
Without details about how "big" the database is, I do not see any risks to upgrade to InnoDB. You should read the introduction made by @teppo and the post written by @ryan
https://weekly.pw/issue/223/
https://processwire.com/blog/posts/using-innodb-with-processwire/
A nice and short explanation by @clsource : https://github.com/joyofpw/how-to-install-processwire#which-engine-is-better-myisam-or-innodb
And of course, ingesting the official mysql dev doc (choose the right version according to your setup):
https://dev.mysql.com/doc/refman/5.7/en/converting-tables-to-innodb.html
You might need to adjust some buffer settings, to get a first insight of it, you could run mysql-tuner, it take seconds to install and run, in order to get an easy to read report (steps below).
### Install wget (mandatory)
```
apt-get update
apt-get install -y wget
```
### Download mysqltuner
```
wget http://mysqltuner.pl/ -O mysqltuner.pl
wget https://raw.githubusercontent.com/major/MySQLTuner-perl/master/basic_passwords.txt -O basic_passwords.txt
wget https://raw.githubusercontent.com/major/MySQLTuner-perl/master/vulnerabilities.csv -O vulnerabilities.csv
```
### Run MySQLTuner
```
chmod u+x mysqltuner.pl
./mysqltuner.pl --user $MYSQL_USER --pass $MYSQL_PASSWORD
```