Yes, ridiculous as it may seem, there were British LI units that were used to outmaneuvre/outflank/surprise the enemy, dressed in the traditional red coats.
Well... They *did* use that tactic despite dressing in something not blending to the surroundings. (I think it was back in American War for Independence from the British) The colours of the uniforms are merely for indicating which sides are they on.
But please let us not go further into the blood shed between American & British in this topic...
Back to the topic... I want to add that having Hvy Wep Platoons in an all infantry army is a good idea as you can gain benefits from the extra long-range hvy fire power. This would allow you to be able to design some fully mobile infantry units (No hvy wep) into the army. Having a certain proportion of fully mobile units & static range units is one of the approach that you can take with "Hvy Wep Platoons". In addition, taking "Iron Discipline" & "Light Infantry" along with "Hvy Wep Platoon" can be very useful as you can make use out of the extra command squad & the Hvy Wep Teams can be very nasty through infiltration.
- One of my suggestion is to take "Rough Rider"... As you are having an all infantry army, you may want to add something that is fast to help the other slow units OR use them as reacting forces.
- The second thing is "Grenadiers + Veterans", and it is good for bringing out the flexibility of Hardend Veterans & Grenadiers.
- OR you can go all hvy infantry style by taking "Grenadiers + Ogryns". They can be very nasty as well since you are basing the army on the tough & fully mobile units. The pts cost for them maybe high, but within that army pts range you suggested (1750 pts), the problem of pts sinking units is slightly smaller...
- If not any of these... Then maybe you could try the new version of Tech-Priest Enginseers with 4 servitors. (Judge for yourself whether they are approved to be updated rule OR not)
But that is up to you...