Short Answer:
Yes it's worth upgrading. Especially if you are running the pressure washer a lot.
As long as the cost to upgrade to a triplex pump fits into your budget, it's worth upgrading. If you are a commercial user you can expect to recoup the up-front cost of the upgrade and save even more over time anyway.
You won't notice any difference in performance though. 2500psi 2.5fpm from an Axial or from a Triplex pump is the same. Generally you will get more water flow from a triplex pump than an Axial pump anyways.
Long Answer:
Triplex pumps are considered a high end and commercial or industrial grade pumps.
Some triplex pumps are high speed and bolt directly to the engine while others are lower speed and are either belt or gear driven.
The RPM of the pump will affect it's lifespan but any triplex is better suited for a lot of hours vs an axial pump and they are considered serviceable pumps.
With regular maintenance ie: check valve & seals replacement as required, unloaders, no leaks in the system and regular oil changes you can expect the triplex upgrade to last a lot longer than an axial pump.
Axial-cam pumps are used in the commercial cleaning industry but are mostly used as residential grade pumps.
These pumps are not considered as robust but they are lower cost by design.
Many axial pumps are sealed and labelled as "no-maintenance" pumps. This just means you run them until they stop working and then you replace the pump.
Keep in mind that no pump, triplex or axial-cam, can stand up to abuse such as overheating or freezing, dirty or low water causing cavitation, and over-cycling unloaders due to leaks in the system.
We can, however, recommend upgrading to a triplex pump every time if it fits your budget since you can expect to recoup the up-front cost of the upgrade and much more over time.
Here is our attempt to compare a pressure washer running at full load to a car or truck on the road:
A contractor or wash bay, truck wash or car wash running 40hrs / week = 2000hrs in a year.
If we compare this to a vehicle in the city we can use 50km/hr or 31miles/hr on average.
This means that: 2000hrs @ 50km(31mi) / hr = 100,000km (62,000miles)
If you expect a pressure washer to last 5 years then you will "comparatively" put half a million kilometres on this pressure washer!
That's a lot of trips to the shop for regular maintenance. If you plan on having a pressure washer last a long time consider purchasing a pressure washer pump that is serviceable.
We hope this helps with your decision!