I wouldn't worry about it. What you have to remember is, yes you may need double the power, but you're not always using all the power from the receiver. If you're listening at a low to normal level and using 30-40 watts, doubling that isn't going to be a problem, especially in a small apt. I own NHT SB2s that are rated at 86db and I used to power them with a Denon AVR-1604 (75watts I believe). I did feel that they were slightly underpowered for that last boost of strength and upgraded to a NAD integrated, but your speakers have a higher rating, and, most of the time, the Denon was just fine.
That is not to say that I wouldn't recommend the 235 over the 135...absolutely I would. However, if you're not willing to swing it now, the 135 (or the Onkyo) should be fine.