If it were me, Id go with the 500, even if it meant I had to spend a little more and replace the electronics.
The 500 is just a better heli for someone newer as it is bigger and can be tamed down more than a 450.
You can find some decent deals on good used servos online. I started out with the 100 dollar value electronics package that I linked a few posts above on my 500.
I put in quite a few flights before one of the cyclic servos let go in flight, causing a crash. I replaced all 3 cyclics at that time and within another dozen flights I had another cyclic servo failure. This is when I said "enough of the el cheapo" stuff and replaced the cyclics again, but this time with a good set of used Align ones. Havent had an issue since and Ive logged a couple dozen flights since.
I am still using the motor that came in that 100 dollar package and it works fine for my skill level. Doesnt have the most power, Im sure...but it gets the job done on the 5s 4000 packs that I run in this heli. Im not at the 3D level yet and just do basic pattern type flying and a lot of FFF(FastForwardFlight) and this motor works good for me with that type of flying.
I never used the ESC that came with it because I had a nice Align ESC and UBEC that I picked up at a swap meet that someone did not use in their 600 Super Combo. And this particular ESC did not get good reviews on the 600, but I am not pushing it anywhere near what someone would be pushing it on a 600 size airframe. But, the original ESC that came with the value kit is still going strong in a Yak54 EP that I have flown quite a bit. So, Im sure it would be adequate to fly the 500.
Also, I did not use the included gyro since I had another "cheap gyro" that I was already familiar with. So, I never used the gyro.
Long story short...you may get by okay with the cheap electronics. Or it may bite you and cause a crash. I wont go out on a limb anymore and say anything either way. I have used the cheap stuff before, and in some cases with planes...still do. But for my helis...I wont skimp any more on servos and speed controllers. Just not worth it.
Dont let the last few sentances discourage you. Because you could easily replace the electronics with better for not much money.
So...500 hands down. Its not even close.