I was considering trying the same setup with 4500 pack of either same or reduced C rating. However at the same C rating the weight difference is 36g and with a 45C rating 66g.
I suspect I would see reduced flight time with the first as 36g is probably not significant, but would like to see the comparison with the 66g difference as I suspect my flight time may be the same or increase. This is assuming that my flying style doesn't demand the full capability of the 65c.
I started the hobby in 2011 with a flybarred T-Rex 550. The recommendation back then was to use 6S
5000mah packs. Until last year, I owned a total of fourteen 6S 5000mah packs ranging from 40C to 65C. When I became interested in Synergy, there was a video where Matt discusses how the lighter 4400mah packs may be a better option for the 550 size class. I now own twelve 6S 4400-4500mah 45C-60C packs, and sold all of my 5000mah packs.
These 4400-4500mah packs work really well with the 550 and 700 class machines. They are slightly smaller than the 5000mah packs, so they are a bit easier to install and unistall, making back to back flights a bit faster. I can feel how the helicopter feels more nimble, too.
I like to fly between 4:30 and 5:30 minutes. If I fly any longer than that, my flying gets sloppier.
I have the timer set to 4:30 on the 550 size Synergy E5. I land shortly after the timer goes off. I fly it at 2400rpm HS which is a respectable head speed. I charge back an average of 2,683mah on those 4400mah packs. So I am using only 61% of the capacity.
On my Synergy E7SE, I have the timer set to 5:00 minutes. I spin the 716mm blades at a little over 2000rpm. I charge back an average of 2,608mah per pack, so I am only using 59% capacity. I don’t like to fly any longer than that. If I used the 5000mah packs, I would just be carrying unnecessary weight.
I also carry between 8 and 12 packs at a time to the field on a bag. The 4400 packs range in weight between 704g and 746g, The 5000 packs range between 802g and 864g. The battery bag feels much lighter with the 4400 packs.