Of course you can.
On the 'weight' issue, the scope 'out of the box', is actually corrector heavy with a dewshield fitted (this depends on the dewshield), but with a normal solid shield, and a Kendrick dew heater, balances much better with a 2" diagonal and eyepiece. In the UK at the moment, the NS11, ships with a 2" diagonal, as one of the 'special offers'. If the eyepiece is a particularly heavy one, you might want to add a small amount of counterweight to help compensate. this is the normal solution when imaging cameras are added.
I suspect the original post you read, was 'hypothesising', because of the fact the scope traditionally shipped with a 1.25" diagonal, when the LX200-12, ships with a 2" unit.
I use a Televue Everbright diagonal with a Pentax SMC 40mm, and it makes a glorious 'wider field' setup. :-)

Best Wishes