I finally got a chance to test my Plant/TA controller under the new changes. I tested the same way I test all new character ideas, running at +1/x8 against Council, level 50 but before incarnates. These were my thoughts with each change:
Seeds of Confusion. The lowered target cap didn't seem to affect me much. My luck with seeds is horrible, I rarely hit more than a few targets, even on live. The plus side is that it usually recharged in under 8 seconds, so I could use it multiple times in the fight. The negative is it did feel like I could have skipped seeds entirely. I expect it's still a valuable power for levelling, but it may not be so useful at 50.
Spirit Tree. This change worked better than I expected. I changed my bind to summon at target location and used it as an opener. The spawns started attacking it immediately, though I couldn't tell how long it lasted since the other power effects made it hard to see.
Spore Burst. I didn't really notice the changes for this power. I ended up dropping it in favor of Poison Gas Arrow since they both have similar effects, but arrow includes -20% damage.
Carrion Creepers. I dropped the procs from it and replaced them with a set of Bombardment. The power performed well and with the other TA powers minions and lieutenants died pretty quickly, but bosses were a lot more difficult.
Vines. Added this into my usual power rotation and it worked really well.
Conclusions: The set felt fine overall with the latest changes. The increase in enemy regen rates seemed to be the biggest problem and clearing the map is definitely slower. I nearly ran out of endurance trying to finish off the bosses. I don't see these changes keeping me from enjoying my plant controllers and dominators or making new ones in the future. Though I would like to see a damage increase on some of the powers.