The 09 Impulse was released in 2009, several months prior to Smart Parts' financial issues which ultimately led to the discontinuation of SP equipment and conversion to GOG Paintball. The 09 Impulse markers are relatively rare because a limited number were sold, and they have little support from the manufacturer. GOG Paintball has some discontinued SP parts, but only while supplies last.
In 2013, a new JT Impulse marker was released after KEE acquired all of SP's intellectual property, but this is not a reinvention of the 09 Impulse. JT Impulses are much simpler in design and none of its parts are compatible. The JT Impulse was designed by GOG and sold by Empire's retailers, but it was also discontinued after slow sales.
09 Impulses were available in mid-2009 with a pricetag of $1000 USD at the time. However, only around 900-1100 markers were sold before SP went out of business several months later (the quantities are estimated).
The remaining information is mostly my opinion based on tech experience with the marker and the community.
The 09 Impulse design is fairly straightforward however the are many deviations from the typical Smart Parts marker design. Reportably it had a different design compared to other SP products of 2003-2008. One of the major changes in 2009 revolved around the concept of SP intending to produce an array of markers and equipment for 50-caliber paintballs, along with the company GI Sports. Smart Parts was leading the prototyping for this effort. A great example of this is the 09 Impulse's modular body design, where the upper section could potentially be swapped out for a different caliber version. I think this is a pretty cool idea in itself, although the problem is 50-cal paintball fortunately never gained enough interest for this to become a selling point. A small number of 50-caliber Impulse parts were made, along with matching barrels and bolts.
In terms of reliability, the 09 Impulse has a lot of strong points, however the internals and overall disassembly of the marker is extremely complex. The eye cover system is particularly intricate. This isn't necessarily a negative feature of the marker, since a complete disassembly is very rare, but it's still a notable factor.
Design wise, there are only a few issues with the marker that I have noticed after using one for several years.
1. The feedneck is a boss-latch system with the same dimensions as Eclipse markers. 09 Impulses were the first Smart Parts marker to use this system instead of threaded feednecks, however the implementation on the 09 Impulse body was extremely poor. The feedneck boss is a separate component which is meant to be heat-shrunk into the body, but the thin shape of the component prevents it from being a reliable hold. There's alos a pair of tiny set screws located beneath the eye covers which are also meant to lock the feedneck boss in place in addition to the friction fit. However, the screws tend to loosen up under regular use, which requires periodic re-tightening.
A factory fix for this is to JB-weld the feedneck boss onto the marker's upper tube. If done correctly, which provides the strength required to keep the feedneck secure. This is currently the best solution to the problem.
2. When cleaning the area beneath the eye covers, the covers themselves hinge away from the body. The eye lenses bend away from the body along with the covers. This system is easy to operate but the problem is the eye wiring is continuously bent back-and-forth along with the hinged covers. This isn't an issue by itself, but it's possible that the eye wiring could combine with paint splatter, combined with grease or other lubricant, combined with other environmental issues (cold weather, etc). A combination of these factors can cause the eye wiring to break on their own.
The good: eye wiring can be repaired with soldering knowledge. The marker uses side-looker anti-chop eyes which are shared with many other markers (Eclipse markers, newer Dye markers, Mini/Axe, and others).
3. People have reported issues with valve stems leaking over time, and the lack of Smart Parts support means there's not much solution for damaged valves. People have tried indexing the valve stem on a lathe in order to add an o-ring shelf with varying levels of success. The biggest issue with adding o-rings is that it requires more force to hold the valve shut, so simply adding an o-ring might not fix the issue.
4. Longevity-wise there are some other common parts with the marker that may simply need replacements over time. Those parts might include the bolt (if it gets overly scratched), electronics parts, regulator base seats, and other items that may wear with use. Fortunately some of the items are shared with DLX Luxes, such as the battery and charging cable hardware. The solenoid is identical to those of other SP and DLX markers (with different wiring).
09 Impulses are still used on the field by various SP collectors. If the item requires technical support, it's uncertain whether or not it would be repairable if the source of the problem cannot be solved by typical o-rings or the afore-mentioned common parts. This is a common issue with many vintage markers, which now includes the discontinued 09 Impulse line.