With just a quick look at pictures of the products, it appears the TX-V2700 has multi-channel preamp outputs. The TSR-7850 appears to lack multi-channel preamp outputs. If you plan to use an external multichannel amplifier in the future then the 7850 won't do the job.
The previous Yamaha AVR offered by Costco had multichannel preamp outputs. It is unfortunate that Costco has cheapened the product. It is hard to know what other corners may have been cut in the most recent product, if any. In some product categories, Costco seems to be moving more toward selling lower-end products made with very low labor costs vs. selling better products at good prices.