Well, for what its worth I never take Warhounds for a number of reasons

- consider my last list at Britcon:-
Strike Cruiser
2x Landing Craft
Thunderhawk
Terminators + Chaplain + 2 x Dreadnoughts
Terminators + Chaplain
Land Raiders
2x Tacticals
2x Devastators
Bikes + Chaplain
2x Thunderbolts
Ok, so I didn't do that well (put that down to my infamous dice

), but I believe the list is reasonably sound. However in this context it does present several features worth discussing.
- The marines do need some cheap activations. Warhounds do provide this, and so do Thunderbolts, Bikes, Speeders and Scouts.
- Marines also need deep-strike capabilities and Warhounds also fill that niche (along with Termies, TBolts, THawks and planet-falling). The choices here tend to determine your army strategy. Without Warhounds you are moving towards some form of air-assault or planet-falling list.
- I always take terminators! Point for point, they are still the most cost effective formation in the army. But they do need support in the form of transport, which adds to their overall cost IMHO (see air-assault debate elsewhere). This means that to be truely effective you usually need one or more THawks to move them where they are needed - or you have to create a strategy around where you drop them. (Ok so I am less good at that). However the presence of THawks also tends towards an air-assault list, at least in part.
(In this context, I welcome the LR Crusader as a balanced alternative for Terminator transport)
Without either Terminators or Warhounds, the Marines tend to struggle in a number of situations that are reasonably well documented. This in turn imposes strategic constraints on the army plays, and hence on the formations chosen. eg TRC says, he avoids titans, Hena majors on cross-fire etc
I am sure that the Marines can do without Warhounds, but am less sure about increasing the cost of Terminators is necessary and certainly not both. I would suggest that Warhounds are less prevalent in the 'fluff' than in the armies generally used in E:A. Consequently I would be in favour of reducing their availability in the list. However, I agree with Meph that Terminators seem reasonably balanced in the context of their inbuilt weakness of relative imobility. So I would not recommend changing them.