Sort of like asking a chrysler salesperson if their cars perform as good as BMW
Yep - could be - I'd still be a bit skeptical as it is the initial start-up that wears the anode's in these bulbs. It is clear that the bulb will not draw any more than the ballast can supply, in fact that exactly seems to be the problem. The power available for start-up (this is where the elements in the bulb ionize the gases in the bulb and supplies the neccessary free electrons for continuous light) is what predominantly wears the elements down. Since these elements are specifically engineered to handle specific amounts of current evenly - it is likely that there will be a change in the elements performance (it may develop a hot spot that wears, or the full element will not be energized, etc.). But after all - we're only talking about 8% difference.
Warranty - affected by this?
- Just my opinion, Half truth: Higher wattage definitely wears elements quicker, because Ballast will fire the elements with a greater amount of current than the element was designed to handle. But the proper current does not. Lower current may, as it will take longer to reach the operating level of the bulb it is accompanied with. There is a reason why these devices are designed and rated for specific values. They may work outside those - but rarely optimally.
Also really, I'm not here to argue for you with someone who gets paid to tell you great stuff about his product... So as I said before:
If you've got the constraints - and you need to use this one - and they told you everything is ok - go for it.