As CrazyFlak says, if quantity of mods is important to you then UP certainly has the greater content.
However I have had no problem adding additional maps and mods to HSFX. My added mods include IL2 1956 Jet Pack and new maps like West Front 1944.
Ashe
Well, since i have few mins to post I'll clear some "foggy" areas. UP and HSFX are so similar yet so Different things.
You cannot compare oranges with apples and same applies for both packs.Ashe said "quantity of addons".
By saying this someone would simply imply that: "Ok UP 3.0RC has more planes, objects, ships, and stuff like this"
However the truth is much more "deep". In UP you have addons that really Evolve IL2 and adds to it other dimentions of experience. You cannot treat "ZUTI's MDS 1.2" like just "another addon". Its a whole different world, a whole different experience that changes multi-player forever by enabling multi-crew positions, resource management and Rearm Repair Refuel possibilities. Stock "MDS" in 4.10.1m has around 10% of the functionality that the MDS 1.2 currently has in UP 3.0 RC. In the same category comes Lutz's AI triggers addon. And then the reworked guns and cannons that took literally 1000s of times testing and researching. You cannot treat the above as just "more addons". They belong to a different category. And you cannot just "add" MDS 1.2 like you add a plane.
Moreover many other things are tweaked in UP like the indexing time of the data in the SFS archives and that's why game although has many GBs of additional data loads even faster that the "stock" one. Let alone the fact that game runs smoother that any other addons package and in some cases even more smooth with more FPS than stock game.
Last but not least the SFS archives of UP are like native ones and don't have corrupted data while for other addons packages this is not true. UP is the only addons package that uses the SAME Format (with better indexing and compression ratio) like the one that 1C/MG used for IL2. No-one mod-package has achieved this so far.
All the above and even more are not in the category of "more addons/mods".
I do acknowledge that we have bugs, hence the "RC" version of UP 3.0, and that our ReadMe is unfinished but we will fix the above before the final version.
We have planes and many maps and repaints that are simply out of ReadMe. We haven't promote UP 3.0RC the way we should but we will try to do so before Final Version comes out.