I think that a rebuild is the most cost effective way to improve your suspension, though it might not be the best way.
There's certainly an advantage to buying a high end shock that's owner rebuildable, if convenience is one advantage you're looking for and if you plan on rebuilding the shock on a frequent enough basis to make your upfront investment worthwhile. I don't know what the current price is of an Ohlins or Penske is (or some other high end brand that I'm not up to speed on), but I don't imagine that $1000+ would be out of the ballpark. You'll definitely get a high performing shock with a lot of advantages, but only you can determine if your riding needs can only be met with a shock at that level.
In 2017 I bought an OEM rear shock from a member on the forum who'd removed it and installed a higher end shock for his bike. The shock was from a 2012, which still fits my 2014 (and probably all the other non ES model years). I don't recall what I paid for the shock. I could have skipped that expense if I'd been willing to send my own shock in and wait.
Norwest rebuilt my OEM shock for $377.08. This rebuild included a spring with a spring rate more suited to my usual two up loaded riding, new valves, seals, compression and rebound shims and fluid. That was of course 2017 pricing; I don't know what the cost would be today. There was a very noticeable improvement in the handling when I installed the shock, and I can say that I was very satisfied with my investment. The shock can be rebuilt, but I would have to send it into Norwest to do it, since I lack the tools and know how. But, even if the current price for a rebuild was more than it was the first time, I think my total cost would still be under the cost of a more high end shock. So if I was calculating the cost of my investment in my suspension at the point of that hypothetical first rebuild between my rebuilt shock and an Ohlins or Penske, I believe my cost would still be less. From the cost perspective, I think I'd have to be on my second rebuild of the Norwest shock before the investment between the Norwest one and the higher end, owner rebuildable ones started to balance out.
I've never had this shock rebuilt a second time.
I think the best way to go would be to invest the money in a high end aftermarket shock, if top notch performance is what you're after, and damn the cost. I'm not that guy; cost is always a consideration when I'm contemplating some sort of improvement to the bike. I'm the kind of guy that'll make his own luggage rack or cell phone mount, but would only use a Koyo or KBC bearing and not some no-name special from Amazon.
I know there's a saying that you only know how bad your suspension is when you finally get to ride a bike with really good suspension, and I think that's true. I was satisfied with the improvements I got from my rebuild, but someone else might not be and could only be satisfied with top of the line.
I think you could probably get a feel for what your best path is if you called one of these suspension companies and talked to them about what they can and can't do for you. I've bought from both Norwest Suspension and Cogent Dynamics in the past, and found both companies to be really helpful and upfront in explaining what they could do with your OEM shock.
Good Luck!
