Is a 12au7 a safe replacement for a 12ax7

Recently I tried the very low gain 12au7 tubes in my preamps phono section.
The reccomended tube for my phono section is a 12ax7.
Other then a huge difference in gain which is desirable the only difference is in heat dissipation.
The reccomended 12ax7 's dissipation is 1 watt and the 12au7 is higher at 3 watts.
I'm not technical ,so I ask
What is the downside of using a 3 watt dissipating tube in place of a 1 watt tube
Many thanks for your reply