The A35 is a gem and I am looking forward to check out the A45 personally. Hey, nothing wrong to admire a good product even they are coming from a competing brand.
I have mentioned previously that not all power rating are identical and comparable, so please don't compare the power rating figure as-is. They are not as meaningful as you expected if you don't know the exact condition of the measurements, for example, are they loaded measurements? What is the loading condition? What is the THD at the stated maximum output? .... just to name a few issues.
On the other hand, power rating (in mW or W per channel) is not the only determining factors in terms of driving and handling of IEM. The other factor is current capacity of the amplifier. Unfortunately this is not something that you can find out from a specification table.
As you have stated, Sony DAPs are based on Class D Digital Amp., and Class D amp tends to have a higher maximum current capacity when compare to a Class A/B amp of the same rating (assuming under the same measurement condition). However, does the 35mA Class D amp in A35 equivalent to 130mW Class A/B amp in N3? I simply can't tell until we test them with a difficult load. In my experience a steady 35mW@32ohm is sufficient for most BA IEMs, but trying to pair it with a low sensitivity Dynamic IEM can be a different story. In other word, if your main interest is BA iems, which covers a large proportion of the market choice, I don't think you need to worry about driving power of the Sony A35, it should work just fine.