I’m a couple days late on this thread.
I actually have that same model spindle (I have lots of spindles like this that I’ve tested, including an smaller 180w version, and a larger one at 800w).
IMO: Both the 300w and teh 180w are great for things like engraving, specfically circuit boards, but if you’re planning to cut some actual material (profiles, pockets, etc) then I would suggest looking into something else.
There is an 800w version that I also have, which comes with a VFD, and you can find in 110v (if that’s an issue) which is much better than the 300w, but even that is severely under powered compared to the colt. At full performance that 300w spindle is only .40hp, where the colt is 1 full hp and IMO gives you really close to that (it’s very difficult to bog down)
I also have the Porter Cable PC450, which is rated as 1.25HP, and has a softer start than the Colt. I also think the PC450 is a little quieter (even though it’s more powerful). I can’t vouch for it’s longevity though. I have used the colt pretty regularly on a mid-sized cnc router for about 6 months and it’s great. The PC450 is only a few weeks old, so time will tell with that one.
How big is the machine you’re building? If it’s not a monster, I’ve suggested many times that people start with a standard Dremel (or clone) while they’re getting their feet wet (and breaking bits, and stalling their routers, etc). For the price (a generic one can be had for around $15) it’s a great way to cut started.