jlick1K has posted on the thread which is 8 years old. I do not know what was like 8 years ago, but situation today is this.
You can verify the balance of SUICA at JR ticket machine at JR station which accepts SUICA.
Also can verify the balance at convenience stores which accept SUICA, cashier can verify the balance, or if you purchase something the receipt will have the balance printed.
As you use SUICA to ride JR trains, as passing by the gate at a station small display on the gate will show the balance.