Compare older Sony ES receiver vs. newer gear?

This question relates to my previous post. I own a Sony ES receiver model STR-GA7 ES. It's a Pro-Logic model with 5.1 analog inputs and is rated at 90 WPC (.05%THD)RMS X 3 up front and 40 WPC x 2 rear. It is from model year 1997 (or '98?). My question is regarding the amplifier section. According to Sony, the front three channels have what is called a "parallel push-pull" design with four output transistors per channel. It is rated to drive 4-ohm speakers up front. Can anyone comment on the quality of this type of amp design relative to newer receivers or separates? The overall build quality seems very solid on this receiver - as good if not better compared to some of the newer "flagship" receivers on the market now. Less processing power, of course, but still excellent feel to the buttons/switches, huge heat sinks, etc.

I know that the Sony ES separates amps of the mid-90's were described in Sony sales literature as having the "parallel push-pull" as a major feature and that their ES receivers were supposed to compete performance-wise with separates of that era in theory. Is this just marketing hype? You don't see this amp design mentioned on any of the newer Sony ES Dolby Digital/DTS receivers. Was the amp design dropped due to high cost or because something better has come along? How does this amp compare to MOSFET? My receiver runs very cool, does that mean it is biased very low and switches to class A/B sooner than other 90W amps? I'm using fairly power-hungry speakers (Hales Revelation 2, 6ohm 86db sealed floorstanding three-way) but they still sound very good on this receiver in my 15' x 13" living room.

Just curious if any Sony fans would care to comment.

Thanks,
JZ