As a long time minecraft player, I think a lot of the player community got spoiled by 1.2.5. It was stable and was around for a really long time. It was basically two different games. A single player game and a different, but similar looking multi-player game. There were oodles of mods out there, and many that were pretty awesome. Many of the awesome mods were not MP compatible. Some like Thaumcraft 2, couldn't be made MP. Other less intensive mods were SSP and MP, but there were two different versions of the mod. One for loading into a single player environment, and a completely different mod compiled for multi-player. And then to make multi-player somewhat friendly to server admins, there came additional ports to environments like bukkit. (There were other environments besides bukkit.) This created at least 3 different versions of the mods. It took quite a while to get all the versions up to date and ported. It was sometimes three times the work. What code worked in one environment may not work in another. The only saving grace for the mod authors is that 1.2.5 was around for so long, they didn't *have* to constantly fix their mods for new environments, so they could work on multiple versions as time permitted and release updates on their schedule.
With Mojang's decision to add in an official modding api, this opened the floodgates to an ever changing slew of major alterations. The first being a unified single and mult-player environment. This was kinda the worse of both worlds for a time. The sync lag was so horrible at first, you could only reliably kill a creeper with a bow. Trying with a sword would get you blown up. Now though, the situation has much improved. Server sync mechanics have gotten better, and it is a lot harder to get out of sync with the server. This change was drastically needed though as MP was horribly laggy in older builds.
MC 1.4.7 I see as the ultimate refinement of the work that was started with 1.3. The major growing pains were gone, and the new features had stabilized and matured. This was a good product. Mojang wasn't done yet though. With 1.5, came new features and new fluid dynamics. (this might be a forge thing, but since I only play modded now, I'm not sure.) Mod liquids were now place-able in the world. Liquids were still not fully fleshed out yet, and 1.6 would bring even more changes to liquids. Now with 1.6 released, the liquid api and foundations are solid. Mods can interact with multiple liquid types in multiple fashions. With this release, mod authors finally have a stable target to hit with a unified way to work with liquids. This makes a cross-mod liquid environment attainable.
MC 1.7 I believe is to finally deliver the infamous lighting and rendering update that we have been promised since 1.0?? No more black render areas and lighting glitches. For some mods, this will be a minor mark, others will have a major change to implement. Even after 1.7 hits, and mods update, Mojang still won't be done. There are a few other areas that still need to be addressed to meet their goal of an official mod API.
To answer your original question, no FTB is not falling behind. They are doing what they need to do. Right now, that is working behind the scenes and working with mod authors on servers like forgecraft 2 and monitoring the forums here, and checking out the custom modpacks like RR and ShneekeyCraft. This lets them see what mods work well together, which ones need tweaking, if any cause unfair balance issues, etc. Every time we post on the forums, we help them define the possibilities that can be done with a mod pack. They don't have time to go through every combination of every mod, so when we need help, they notice, and when we show off our awesome builds, they notice. Frankly, I absolutely love the FTB forums. It was always so hard working on the minecraft forums as each mod had their own thread. You may get a reply to a question you asked, but it might show up 3 pages later... Several issues I've run into were nothing that were caused by one mod. Only in combination with other mods. FTB is an awesome place for assistance and help with this since they are about the mod *pack*, and not individual mods.
So, everything is being done in its own proper time. It will get done and updated when it is ready. I don't expect or even want them to do so before it is.
