When I special ordered my 25' Safari back in October of 2003, only handful of the 25' or larger Classics had the 15k BTU A/C unit as an option. I requested the 15k unit for my 25' Safari. I did receive some suggestions from both folks here on this forum and from the factory (via the dealer) and from the dealer themselves as well not to go this route for a variety of reasons, none of which panned out.
My question back to them was that it was a Classic option, why can't it be installed in a Safari since internal size and construction was the same between a 25 Classic and a 25 Safari (they all start out the same way and get odds and ends added as it goes down the line and becomes a "Classic").
It cost me I believe about $450 to upgrade from the standard LS upgraded unit (13.5k) which was already an upgrade from the 11k unit that comes standard at the time of construction, which most likely won't be your cost doing a total swap out, but you most likely sell the 11k unit.
The 15k Penguin is a great unit. I have zero complaints. Dometic I believe owns and builds the Penguin. In direct sun with high outdoor ambient temps, the 15k unit can keep the inside cold enough to hang meat (ask folks who have been to a rally with me
). The newer models I've heard are even more reliable than my "legacy" model.
I would not hesitate to recommend considering the Penguin low profile 15k unit. Mine has a heat pump, not a strip with it and also has the comfort control system which controls both the A/C and the furnace for seamless service. Even without the Comfort Control System, I would still take a 15k unit every day of the the week and 2x on Sunday.
If you look closely at new models out there for the past several years, many now have the 15k unit (regardless of model) that are 25' or larger with plans to be in warm climate (which is pretty much everywhere these days during the summer months).