It's worth the added cost. You want to keep the OEM spring rate and use the higher quality Toyota mounts, insulators, and bearings anyways. The quick struts are notorious for using cheaper components and the spring rates are not matched to each vehicle.

 

For what its worth, when I did a complete suspension rebuild on my 2008 ES 350 I contacted KYB directly. They actually communicated with me quite a bit. They design to factory specs. After my conversations with them, I'm confident they do. Why would they not? Especially in the case of the 2008 ES, since they were the OEM strut supplier. KYB was stamped on the factory struts. The quick strut replacements were identical, factory paint marks and all.

I often read the aftermarket mounts are inferior to factory, but I'm not sure why or how KYB would run that in their factories. One assembly line is much easier to maintain than two. Same with raw materials and such. Plus, warranty servicing is expensive for them. Could it be that people who complain of this just didn't use a torque wrench? Used the Guudintight method ?

One email response from KYB is embedded in my account of this if anyone is interested.
https://www.clublexus.com/forums/es-5th-gen-2007-2012/930037-2008-front-strut-entire-assembly-options.html

From their website
KYB is well known as an Original Equipment supplier to new vehicle manufacturers around the globe. We use the same materials, techniques and facilities to build our Aftermarket products.
https://www.kyb.com/about/kyb-in-north-america/

 

If you do your homework and the aftermarket supplier is also the OEM, and you verify the specifications, you can sometimes find a decent quick strut. I think KYB is an example where its possible. The advice I'm getting is from close friend who is a 25yr Toyota mechanic. He is also the one who complains about quick struts failing or performing poorly. He has said some quick struts can be okay as well but in general when viewed side by side with the OEM you can see the differences in the thicknesses, the stamping, materials, etc.

For me replacing the suspension is a 10yr job and will probably only ever be done once, maybe twice on the lifetime of a vehicle I own. I'm not doing my own auto maintenance and the extra cost to rebuild the struts doesn't add to much over the lifetime of the vehicle and I have confidence it will last as long as the original.

 

I totally get the cost factor when amortized. I do my own work, and check the parts carefully My philosophy is if the parts are identical, why pay more? I will admit I'm not nearly picky with a front wheel drive Lexus as I am with a high performance BMW that has unmatched power and handling to anything we are talking about here. Toyota suspensions are very forgiving, where a BMW is not. A front wheel drive toyota setup can practically be worn down to the metal and still be somewhat driveable. A BMW would be all over the road - thats the price you pay for ultimate handling. I haven't dealt with rear wheel drive Toyota's/Lexus, they may be a different example. Even so, I do not use BMW parts, because its well known that certain after market companies are the OEM. Those are the parts purist go after, because the only difference is a sticker or a stamp, and you can save up to 1/3 the price. Some parts even go so far as to simply scratch off the BMW markings.. And of course, there are after market BMW parts I would not buy and if the only choice is between BMW high priced part and a crappy after market, I will pony up the bucks. My Formula on the other hand, is an eternal search for NOS parts - very hard to find!