I am a beginner to intermediate fly angler (3 yrs exp), and 90% of my fishing is high mountain lakes during the summer on long day hikes and long backpacking trips in the Rockies. The only rod I've ever carried is a Temple Fork 9'6w 4-piece rod and reel that came in a $200 starter package from Bass Pro Shops. I did buy a nicer reel for it later, and put a sinking line on the original cheap reel.
As I've become a little better backcountry angler, I am ready to upgrade to a nicer setup. And I was possibly thinking about going to a little smaller setup like a 8.5 foot 5 weight, with a little bit more control on delicate presentations and fishing the smaller streams connecting the lakes. But also, the high lakes can be breezy places, and sometimes I constantly fight the wind. I've read that 9'6w rods are better for cutting into the wind, obviously?
And sometimes you need to make some long casts on lakes (which I am not good at)..........in fact I would like to emphasize I am not a good, experienced caster. But I have my moments.
I don't really know the brands too well, but I've heard of all the biggies, St Croix, Sage, etc. I want to spend up to $300 or so. And do I need a new reel if I buy a 8'5w, or can I use the one off of my 6w? And I obviously need a 4-piece rod and I already have a good pack case for it.
The reel from the 6 weight will be fine. I would think any of the four piece rods that meet your price point would be fine. When you said 'backpack rod' I was thinking 6 piece like are made by Orvis & Hardy, I think Cabela's may still sell a 'Stow Away' rod also. I don't have any 6 piece rods but always thought a Hardy Smuggler would be cool for traveling on the motorcycle. I'll be watching the thread to see what suggestions you get coming in.
I thought of another option that could give you two for the price of one, so to speak, but it depends on the rod action you prefer.
With a single fast action 5 WT you could also cast a 6 WT line on a spare spool if the wind is serious issue. A good, fast 5 WT could also handle your 6 WT sinking line, maybe. Then you'd only have to carry multiple spools rather than multiple rods.
The TFOs seem to be really great rods for the money, so not sure what you want to move up to. You could find an old Sage XP on ebay (a fast rod that could certainly handle a line up) or cast one of the new VXPs (which I've heard mixed reviews of) that is supposed to be similar to the old favorite but lighter, and not ridiculously expensive for a new fly rod, <$500. But again, this all depends on the action you like. Keep us posted!
I flsh RMNP streams and lakes >90% of the time. For day trips, I take 1 rod depending on conditions. Nymphing or windy conditions and I'll use my 5wt loomis glx.
For overnight trips when it may be difficult to guess at multiday conditions, I carry 2 rods in the same tube. A 9' 5wt for windy conditions and an 8' 000TXL for calm conditions. I have been pleasantly surprised at the number of occasions when I've been able to use the 000. Dry fly fishing with the 000 is an absolute blast, especially lake inlets and outlets.
I'm by no means an ultralight hiker/camper, so I don't mind carrying two rods and 2 reels. I've found that the rod case is just about the heaviest part of the setup, so 2 rods in 1 case works for me.