AFTER ACTION REPORTWow, this was probably the closest and longest game I ever played! ÂÂ

Very, very enjoyable, this is the kind of game that makes you loves EA even more. ÂÂ
OK, a few comments.
V9.1 modifications- 20 cm move for Warriors > This is great. No longer do the Warriors slow down their swarm. Please, pretty please, implement this in the next version as it really helps those poor infantry swarms.
- Lictors with Sniper > never really used, they only engaged the Rough Riders and the Sniper ability didn't make any difference. But I think it's better than MW.
- Hormagaunts with 2xCC5+ > This is OK. I still think First Strike would help them and the infantry swarms a lot, but I can live without it. Would 2xCC5+, FS and +25pts for 4 Hormagaunts be too much?
- All units ignore difficult terrain > Love it. I quickly lost count of the number of difficult terrain tests I should have made without this rule.
- +2 to Engage > This felt right. Tyranids can finally do the only thing they are good at without fear of failing the activation (unless you retain and have BMs, but that's perfectly normal).
- +2 to rally rolls > This felt good, perhaps a little too good even. I think it's OK to see Tyranids rally easily, they should, but I may be biased. ÂÂ

+2 puts them just above Marines in terms of rallying. +1 is just like Marines.
And now the big one: those damned infantry swarms are, as Jeridian put it, a liability. My Titans (Harridans included) did most of the work while none of my Assault Swarms did anything but lose assaults. Whether I Engaged or not made no difference.
For both big engagements involving my Assault Swarms, I ran a few numbers comparing the different proposals:
Engagement #1 -  Storm Troopers (SHT's in support) vs. Assault Swarm 1IG casualties > 2
'nids casualties > 9
Combat resolution
- Normal rules > +7 to IG [(9 + 1 (Inspiring)] - [2 + 1 (more units)]
- "Full Expandable" > +1 to 'nids [(1 (Inspiring)] - [2 + 1 (more units)]
- "1/2 Expendable" > +3 to IG [(4 + 1 (Inspiring)] - [2 + 1 (more units)]
- 6+ save in assault > +5-6 to IG, depending on the saves
- CC4+, First Strike to Hormagaunts > +7 to IG (no Hormagaunts in CC)
Engagement #2 -  Assault Swarm 2 (Harridan in support) vs. Infantry company & SentinelsIG casualties > 5
'nids casualties > 9
Combat resolution
- Normal rules > +3 to IG [(9 + 1 (Inspiring)] - [5 + 1 (more units) + 1 (less BMs)]
- "Full Expandable" > +6 to 'nids [1 (Inspiring)] - [5 + 1 (more units) + 1 (less BMs)]
- "1/2 Expendable" > +2 to 'nids [(4 + 1 (Inspiring)] - [5 + 1 (more units) + 1 (less BMs)]
- 6+ save in assault > +1-2 to IG, depending on the saves
- CC4+, First Strike to Hormagaunts > Hard to tell, but 2-3 less hits from IG, so 1-2 less casualty on the 'nid side for something like +1-2 to IG.
>>> So the "Full Expendable" option is clearly too powerful, as both times it turns a defeat into a victory. "1/2 Expendable" looks like a good "equalizer" option: it gives 'nids a better chance of winning by a close margin or at least of not losing so badly. The other options don't seem to make much of a difference.