I did it for 18 months. Feasible? Yea, sure. But here are some caveats you should be aware of.

Trains do run late...even the keystone line.

Accidents on the line happen and delays can happen...which can leave you super effed in regards to time. The logistics of it all are terrible...even if say you live very close to 30th Street Station, there are many points of failure from commuting by train to HBG each day. Even still...unless you have a job at Harrisburg University or the Capital building...where walking isn't bad...you'll be huffing it to get to work.

Eventually my stint of that commute ended, but the commute can be brutal. Plus the monthly passes and only a small discount comparably, so you'll feel the drain of tickets quickly.