At first, I was ok with paying the price for the matrix or mk pro or coronation ace because I whole heartedly expected to be getting the Jackson Debuts/Premieres, which are cheaper than the RF3. But since the RF3s are better for my feet, the total with RF3 + MKs are bit over my budget.* Time to take a pause here. It's difficult for me to see what's going on because the relative HK prices appear to be substantially different from the relative US prices for different gear. [I realize there are differences in duties, tariffs, exchange rates, shipping fees, ....] You were willing to pay for Matrix Legacy blades because of the color options, but you are now hesitating about the MK Pro. Let's back up and consider various issues.
* You started here.
Now, is this a coach that you just happened to chat with, or a coach that you plan on taking private lessons from? Did the coach just say casually, "Oh, just go with the MK Pro," or does the coach strongly recommend them to all their students? Some coaches are well versed with the characteristics of specific blades and teach accordingly. Check whether this is the case.
* Don't worry about which blade will make an easier transition from rentals. The transition will be substantial regardless, and will be mainly dictated by breaking in a proper pair of boots. As for an 8-ft main rocker being more stable than a 7-ft main rocker for a beginner, I don't know. That's certainly been the trend for beginner blades. MK Pro and Wilson Coronation Ace are typically listed as intermediate blades. They are not overblading for beginners; the major negative relative to beginner blades is the extra cost. But note that prior to 2015, both MK and Wilson beginner blades (below the Pro and Ace) all had nominally 7-ft main rockers. And I mean for eons prior to 2015. They then suddenly switched to an 8-ft main rocker. Wilson no longer sells beginner blades. MK still offers the Flight and Galaxy, and posts this explanation on their website:
"The MK Flight was released in 2015 to meet the specific needs of the entry level skater. As skaters’ needs developed and changed over the years, the team at MK set out to create a blade that satisfied the elementary market. Unlike our beginner blades of the past, the Flight’s profile has been flattened to perfectly suit boot/blade combination sets."
Perhaps an experienced coach can chime in here.
* But, regardless of your first blade, your next blade will likely have a 7-ft main rocker. The only mainstream intermediate blade with an 8-ft main rocker currently on the market is the Ultima (traditional) Legacy 8. So one can argue that if you start with a Pro, you can stay with a Pro.
* Another consideration that pops up is whether a cheaper beginner blade actually saves you money in the long run. That depends on the relative frequency of sharpening and the cost of sharpening (I currently pay US$35/sharpening). I don't have a definitive answer for this. I answered in a concurrent thread:
You can look at the other thread for more details.
* If your shop has a Flight and a Pro of the same length in stock for you to play with, then compare the lift angles. See the video "Lift Angles" on the Paramount site: https://www.paramountskates.com/videos. Watch the entire video for your education, but pay particular attention starting at ~1:50 for how to do a simple lift angle comparison at the store. If the lift angles are approximately the same, the spin rockers are close.
* Regardless, I agree with Diana. If you don't want to spend the money on a Pro right now, the priority is to get out of rentals. Then go with the RF3 Pro + Flight and upgrade the blades later (assuming the boots are still OK when you've advanced sufficiently to merit a blade upgrade). Whether this saves you money in the long run is not clear.
The coach I talked to is the coach I'm currently taking lessons from (group of 3 students including me). But it did seem that he found which boot worked for him very early on and never looked back lol (because when I asked him about his opinions on Jackson or Risport, he said he's only ever skated on Edea). He said he recommends the MK Pros for everyone.
I think prices in HK are generally better bc from what i know, there aren't import taxes