Lost Mines/Icespire Peak Combo Campaign Milestone/XP Hybrid, Does this look resonable?

Question

I'm setting up to run Lost Mines and Icespire Peak at the same time. I wanted to use milestones instead of XP but I didn't want to feel like progress only happened at certain times so I assigned each quest/location a point value depending on the level it is balanced for and then assigned level-ups based on how many progression points they've acquired. I feel like the point values are good but I don't know if the level-up values are good.

They reach Phandalin by level 2 if they go to Cragmaw Hideout. Level 3 by the time they are 2/3 done with the level 2 quests. Level 4 part way through the level 3 quests, even level 5 if they strive to complete everything. Otherwise, level 5 by the time they finish the level 4 quests. Then level 6 after finishing the level 5 quests.

Should I adjust anything or does this look good? It's intended to be a slower leveling pace and I'm expecting them to want to do everything they can find to do. Minor things that only give gold rewards have been excluded from the list and won't count toward level progression.

Level 1, 0 Points:
Level 2, 2 Points:
Level 3, 12 Points:
Level 4, 25 Points:
Level 5, 40 Points:
Level 6, 55 Points:

Level ?
Phandalin
Falcon's Hunting Lodge (IP)
Shrine of Savras (IP) 1,3,5 points extra

Level 1 Quests
4 points, 4 total
Goblin Arrows (LM)
Cragmaw Hideout (LM)
Gnomengarde (IP)
Dwarven Excavation (IP)

Level 2 Quests
12 points, 16 total
Redbrand Ruffians (LM)
Logger's Camp (IP)
Delivering the Supplies (LM)
Halia's Job Offer (LM)
Redbrand Hideout (LM)
Finding Iarno (LM)

Level 3 Quests
24 points, 40 total
Butterskull Ranch (IP)
Tower of Storms (IP)
Umbrage Hill (IP)
Conyberry and Agatha's lair (LM)
Old Owl Well (LM)
Ruins of Thundertree (LM)
Wyvern Tor (LM)
Cragmaw Castle (LM)

Level 4 Quests
8 points, 48 total
Mountain's Toe Gold Mine (IP)
Wave Echo Cave (LM)

Level 5 Quests
15 points, 63 total
Axeholm (IP)
Dragon Barrow (IP)
Woodland Manse (IP)

Level 6 Quests
Circle of Thunder (IP)
Icespire Hold (IP)

Answer 1

Mostly yes...

In general - it seems fine. Of course, if players would do everything they can - they'd be level 5 by the end of 3rd level quests, but one level difference is not that great and due to low number of 4th and 5th level quests - they'd quickly catch up with intended progression.

...but there are some things to consider

First - it would be quite lengthy campaign. Each of those quests is designed to take at least 3-4 hours and can take longer (we've spent about 10 hours exploring Axeholm, for example, mostly because we couldn't believe how many empty rooms without anything interesting are there and kept searching for secrets that weren't there). So, you may want to talk to your players to see if they want to spend that much time without progression.

Second - players would be getting double loot per level, which may lead to quite well-stocked party by the end Lost Mine adventures.