To start I'm going to re-post the justification for Storms from the other thread:
GlynG wrote:
In W40k rules and background Scouts have never (not in any edition) had access to Rhinos or Razorbacks – they’re not vehicles they use. While they could still operate fine on a W40k battlefield on foot, they would have been very poor in Epic without any transport vehicles, so for the lack of any other good option they were allowed access to Rhinos and Razorbacks. A few years ago GW finally released a dedicated transport specifically for transporting SM Scouts the– the Land Speeder Storm (which carries 1 stand and is armed only with 1 heavy bolter) and I believe we should adopt the proper Scout transport in the Epic list. The Land Speeder Storm has been in the Raven Guard list here for a while now, but it is not specially associated with the Raven Guard – Storms are used by all chapters.
These are Land Speeder Storms (just in-case any of you aren’t familiar with them):

The stats for a Storm (from the Raven Guard list) are:
LV 35cm move, 4+ armour CC6+ FF5+
1 x Heavy Bolter 30cm AP5+
Notes: Skimmer, Transport (May carry 1 Scout unit)
Basically identical to a Tornado, without the second weapon.
Note the Storms do not themselves have Scout. To compare them to Razorbacks:
Advantages: Storm is a Skimmer, Storm has 4+ armour, Storm has +5cm move, Storm is realistically a more practical vehicle for scouts and looks cooler

Disadvantages: Storm only has a single heavy bolter, Storm is a LV, high cost as Storm upgrade is for 4 whereas most people have only 1 Razorback and only occasionally 2-3.
If Scouts are made 175 then I suggest the Land Speeder Storms upgrade should be +75 points for 4. The formation has been tested at 250 in the Raven Guard list and though the upgrade cost could still be +100 for the Storms 275 sounds a bit high for the formation. Part of the issues with 150 or 175 un-upgraded Scouts come from their cheap cost adding to activation count and allowing a few formations to be used together and this is less of an issue with 250-275 points units.
Also, crucially, all Land Speeders in the Raven Guard list also have a special ability allowing them to Planetfall (it’s one of the defining featured of the list), so it is not unreasonable for the Storms cost to be cheaper here without that. The Raven Guard list has planetfalling Land Speeders and half a dozen new units, so we wouldn’t be stealing its thunder by making the Storms generally available – Neal Hunt also said in the other thread that they are the one new SM unit he would be ok with retroactively including in the main SM list.
In-case anyone notices and wonders about them, yes, they do also have a small underslung grenade launcher, but even in W40k this ‘Cerberus Launcher’ doesn’t shoot or kill as such, but just gives the Scouts a small bonus if they charge into close combat on the turn they disembark. It fires very short projectiles which stun and blind the enemy, temporarily reducing the enemy leadership should they loose the combat. Basically, it’s an effect too inconsequential to be relevant to epic or the unit stats.
Another re-post from the other thread on proxying Storms:
GlynG wrote:
Steve54 wrote:
LS Storm - IMO as far as possible 'core' lists should be freely available model wise
There are a range of proxy options available depending how much time/effort a player wants to spend. A regular Land Speeder as is could be a simple Storm proxy just painted in camo-colours (the Forge World books show SMs occasionally use camo and despite GW’s default colour scheme the Storm is the vehicle camo makes most sense for). An additional idea is perhaps to clip the circle bases off and attach a Scout model or two to the sides as though they are holding on/shooting in transit/disembarking – the current metal Scouts can be bent and re-positioned very easily.
Optionally, if a more complex/detailed conversion was desired, a regular Land Speeder could be sawed in half horizontally, with the two halves then pinned together with a gap and the gap filled with a layer of plasticard. Possibly appropriately sized plastic rod could be used to add a third exhaust to the back if particularly bothered. Lastly there’s always the possibility a suitable proxy could appear through CAD at some point in the future, though this isn't necessarily needed.
In an ideal world I’d much prefer getting rid of both Rhinos and Razorbacks for Scouts, but that might be a step too far for people at large to be happy with.
A good potential compromise we could agree on and test could be to add Storms and remove Razorbacks, but leave Rhinos. Then people with existing transports painted up for their Scouts can still use the basic Rhinios (and the Razorback(s) elsewhere), while the rest of us get to use Storms. If they are added in I would often use 1-2 formations with Storms in my lists.